EARTH CUTTING APPARATUS, SYSTEM AND METHOD CROSS-REFERENCE TO RELATED APPLICATION This application claims priority from South African provisional patent application number 2021/06041 filed on 23 August 2021, which is incorporated by reference herein. FIELD OF THE INVENTION This invention relates to earth cutting, an earth cutting apparatus, an earth cutting system and an earth cutting method. More particularly, but not exclusively, this invention relates to deep working of earth or soil for preparation and treatment of the soil or earth. BACKGROUND TO THE INVENTION The tilling or ploughing of soil for agricultural purposes involves various techniques and equipment, many of age-old origin. These techniques and equipment have evolved in modern times to include a wide variety, or sets, of working tools such as ploughs and rippers of various design and construction and additional working tools such as shears and toes which work through the soil. These ploughs and rippers are dragged through the soil by driving systems, such as tractors. There are many possible combinations of driving systems and the various working tools, each with a specific application in agriculture. Some of these devices are specialised so as to create soil conditions suitable for the cultivation of a specific annual or perennial crop. Traditionally, these ploughing or tilling systems are used to loosen the soil to a certain depth and to allow for root development and the penetration of water and nutrients, into the soil. Water and nutrients are generally introduced on a top surface of the soil. These ploughing and tilling systems have become more sophisticated over time and have been developed to penetrate the soil to greater depths while also achieving a wider reach. Thus, the effectiveness of soil loosening and turning as well as the effectiveness of introducing various substances including fertilizers into the soil have been improved over time, however these improvements were of limited extent. A measure of the efficacy of a ploughing or tilling system is a required pulling or pushing force (also referred to as a draft force) used while tilling an area of soil. This required pulling or pushing force is affected by factors such as increased soil compaction which, in turn, results in increased soil strength and bulk density. Soil compaction and thus bulk density increase with increasing depth below the soil surface, which may result in: · An increase in the amount of energy input required for tilling; · An impediment in the growth of plant roots particularly at low moisture levels; · Reduced water penetration and reduced moisture retention capacity of the soil; · Diminished void spaces for holding adequate water-air-nutrient mixtures; and · A reduction in the magnitude of soil pore sizes due to the increased soil bulk density, which depraves crops of water and nutrients. Even in conservation tillage systems, including minimum or no-till practices, the negative effects of compaction may accumulate over time. These negative effects may occur even in virgin soils. A problem encountered in the field is that the amount of energy needed to provide the draft, pulling or pushing force required by conventional tillage implements increases at a rate greater than a proportionate increase in tilling depth. This has the effect of limiting deep tilling as a result of increased operating costs and also increased wear on tilling equipment. The effectiveness and efficiency of a tilling system is determined by the design of the working tool set used to cut through the soil including shears or blades of a plough, in the case of ploughing and the toes or tips of a ripper in the case of ripping the soil. Conventional tilling, invariably using narrow tilling tools, may rely on a three-dimensional mode of soil-zone failing in front of the tool as well as at its sides. A critical depth of 600 mm may be postulated for this mode. Changing and improving soil-failure by increasing the working-depth to tool-width ratio and/or working below the critical depth has the effect of requiring increased draft, pulling or pushing forces as well as significant wear of mechanical components. These increased pulling or pushing forces have the result that the power needed increases exponentially. However, a side effect of working below the critical depth may also be a reduction in soil disturbance with an increase in soil compaction. Increasing environmental awareness of industrial and mining operations and the impact of their activities, including the pollution of the soil, have also raised an increasing need for the rehabilitation and remediation of soils thus polluted. To achieve soil conditions which will be useable for agricultural, forestry or environmental purposes as well as ecological interactions which do not tolerate any form of pollution often requires the soil be penetrated and moved to depths greater than normally required by agriculture, while soil ameliorants, fertiliser or the like are introduced at the same time. The known devices, systems and methods may not be able to perform tilling beyond the critical depth, or the known devices may be complex and expensive. The applicant considers there to be room for improvement. The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge in the art as at the priority date of the application. SUMMARY OF THE INVENTION In accordance with an aspect of the present disclosure there is provided an earth cutting apparatus comprising: a plurality of articulated elements including at least a first element and a second element hingedly connected to the first element, the second element defining an aperture therein; and an earth cutting hook including a proximal end which is affixed to the first element and an earth cutting end capable of slidably extending through the aperture of the second element so as to be moveable between a retracted position and an extended position, wherein hinged movement of the second element relative to the first element in a first direction causes the earth cutting end of the earth cutting hook to slidably extend from the second element to the extended position for operatively cutting earth, and hinged movement of the second element in an opposite direction causes the earth cutting member to slidably retract to the retracted position. The earth cutting hook may have a hooked portion near its earth cutting end. The hooked portion may be angled, or it may have a claw-like shape. The hooked portion of the earth cutting hook may be generally planar. The earth cutting hook may include a mounting plate near its proximal end, so as to enable the proximal end of the earth cutting hook to be affixed to the first element by way of the mounting plate. The mounting plate may be transverse to a plane of the earth cutting hook or transverse to a plane of the hooked portion. The first and second elements may be articulated plates. The first and second elements may form part of an articulated band of plates or elements having a plurality of first and second elements arranged adjacent one another. The articulated band of elements may be provided around an idler wheel and a driver wheel for rotating the band of elements in use. The earth cutting apparatus may include a plurality of earth cutting hooks. The plurality of earth cutting hooks may be provided on the articulated band of elements. The earth cutting hooks may be configured to move between their extended and retracted positions as the articulated band of elements moves around the driver and idler wheels in use. The earth cutting hooks may be arranged in one or more rows along the articulated band of elements. The earth cutting hooks may be arranged in parallel rows along the along the articulated band of elements. The earth cutting hooks may for example be arranged in a staggered formation along the articulated band of elements. Each earth cutting hook may include a plurality of hooked portions, claws or teeth near the earth cutting end of the earth cutting hook. For example, each earth cutting hook may include two hooked portions or claws, or three hooked portions or claws, or more than three hooked portions or claws. In the extended position of each earth cutting hook, the one or more hooked portions may at least partially extend through one or more apertures of the second element, so as to be capable of cutting earth. The earth cutting hook may be configured to perform a clawing motion as it moves from the retracted position to the extended position. This may enable the earth cutting hook to pierce and cut earth in use. The first element may also include one or more apertures therethrough, for one or more further earth cutting hooks to, at least partially, extend through in use, for example in the case of the earth cutting hooks being arranged in one or more rows along the articulated band of elements. The aperture in the first and/or second elements may be sized to accommodate the hooked portion of the earth cutting hook therethrough. The aperture in the first and/or second elements may be arranged to clean the earth cutting hooks as they retract or move from the extended position to the retracted position. Edges of the aperture(s) may be arranged to scrape the earth cutting hooks as they retract or move from the extended position to the retracted position, thereby causing earth, mud or other material to be dislodged from the hooked portions of the earth cutting hooks. The aperture in the first and/or second elements may be shaped as a slot. The slot may be sized to slidably accommodate the earth cutting end of the earth cutting hook therethrough. Each of the first and second elements may include one or more earth cutting hooks affixed thereto. Each of the first and second elements may include one or more apertures for further earth cutting hooks to extend through. The one or more earth cutting hooks may be affixed to a radially inner surface of the first and/or second elements. The hooked portions or the earth cutting ends of each of the earth cutting hooks may be arranged to extend radially outwardly from the first and/or second elements as they move between their retracted and extended positions while the articulated band of elements is rotated around the driver and idler wheels in use. In accordance with another aspect of the present disclosure there is provided an earth cutting hook for an earth cutting apparatus as defined above, the earth cutting hook comprising a proximal end which is capable of being affixed to the first element, and an earth cutting end capable of slidably extending through the aperture of the second element so as to be moveable between a retracted position and an extended position in use, the earth cutting hook further comprising a generally planar hooked portion near the earth cutting end of the earth cutting hook. In accordance with another aspect of the present disclosure there is provided an earth cutting system comprising: a band of articulated elements including at least a first element and a second element hingedly connected to the first element, the second element defining an aperture therein and the band of articulated elements being provided around an idler wheel and a driver wheel for rotating the band of elements in use; and at least one earth cutting hook including a proximal end which is affixed to the first element and an earth cutting end capable of slidably extending through the aperture of the second element so as to be moveable between a retracted position and an extended position, such that when the band of articulated elements is rotated, the earth cutting hook moves to the extended position when the earth cutting hook is at a first location relative to the idler wheel for operatively cutting earth, and moves to the retracted position when the earth cutting hook is at a second location relative to the idler wheel. In accordance with another aspect of the present disclosure there is provided an earth cutting method comprising: rotating a band of articulated elements by a driver wheel around an idler wheel, the band of articulated elements including at least a first element and a second element hingedly connected to the first element, the second element defining an aperture therein, utilising at least one earth cutting hook including a proximal end which is affixed to the first element and an earth cutting end capable of slidably extending through the aperture of the second element so as to be moveable between a retracted position and an extended position; and driving the driver wheel to operatively rotate the band of articulated elements around the idler wheel such that during rotation of the band of articulated elements, the earth cutting hook moves to the extended position when the earth cutting hook is at a first location relative to the idler wheel for operatively cutting earth, and moves to the retracted position when the earth cutting hook is at a second location relative to the idler wheel. Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: Figure 1 is a three-dimensional view of an exemplary earth cutting apparatus and system; Figure 2 is a side view of the earth cutting apparatus and system of Figure 1; Figures 3-4 are three-dimensional views of examples of earth cutting hooks that may be used with the earth cutting apparatus and system of Figures 1 and 2; Figure 5 is a flow diagram of an exemplary earth cutting method; Figures 6-7 are three-dimensional views of further exemplary embodiments of articulated elements having earth cutting hooks mounted thereon; Figures 8-9 are three-dimensional and side views of an example embodiment of an earth cutting unit; Figure 10 is a three-dimensional view of the exemplary earth cutting unit of Figure 8 being drawn by a vehicle in use; and Figure 11 is a three-dimensional view of another exemplary embodiment of an earth cutting unit. DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS There is disclosed an earth working device or a soil working device, as well as an associated system, method and earth working hook. The earth working device may also be referred to as an earth cutting apparatus. The soil working device and system may include a plurality of links, grousers or plates that are arranged in a chain rotatable with an engine or electric motor around a power transferring member or driver wheel and a freely rotating member or idler wheel. The links or plates may also be referred to as articulated elements. Hydraulics or another moving mechanism may be provided for lowering the earth working apparatus or system into the ground or soil to work the soil, at a required depth. Aspects of the present disclosure may enable soil working at depths greater than 600 millimetres. The earth working apparatus or earth cutting apparatus may also be referred to as a claw-slide earth cutting apparatus or a hook-slide earth cutting apparatus. The earth cutting hook, earth cutting member, claw, tooth or prong may be provided on two successive plates of the chain of plates. Rotary motion or pivotal movement of the plates relative to one another may cause the earth cutting hook, claw, prong or tooth to protrude or to extend from an adjacent plate next to the plate on which the hook is mounted. In use, the earth cutting claw or hook may rip, pick, perforate or pierce the soil or earth when it is moved through the ground. The soil working apparatus and the soil working system may be provided on a vehicle such as a wheeled or tracked vehicle for conveying the soil working system as it is used to work or prepare the soil. The earth cutting apparatus, system or method disclosed herein may also be referred to as a soil deep working apparatus, system or method. The present disclosure may find application in a variety of fields, including agriculture, mining, engineering or any field where earth may need to be worked, excavated, or tilled. Throughout the Figures, similar features may be designated by like reference numerals. Referring to Figure 1, there is shown an earth cutting apparatus (10) or earth working apparatus and an earth cutting system (100) or an earth working system. The earth cutting apparatus (10) includes a plurality of articulated elements (12.1 to 12.n) including at least a first element (12.1) and a second element (12.2) hingedly connected to the first element (12.1). In the present exemplary embodiment, the first and second elements (12.1, 12.2) are articulated plates and form part of an articulated band (14) of plates or elements having a plurality of first and second elements (12.1, 12.2 to 12.n-1, 12.n) arranged adjacent one another to form the band or loop. The articulated band (14) of elements are in the present embodiment provided around an idler wheel (16) and a driver wheel (18) for rotating the band (14) of elements in use. The idler wheel may also be referred to as a roller. Any (n) number of elements may be used and (n) may be an even or uneven number, depending on the particular application. In the present embodiment, n=32, so 32 plates or elements may be arranged in the band (14) or loop. However, for the sake of clarity, and to facilitate explanation, reference is made to a first element (12.1) and a second element (12.2) which may rotate along with the band (14) of elements around the driver (18) and idler (16) wheels in use. In the present embodiment, a plurality of first elements (12.1 to 12.n-1) may be similar to one another; and a plurality of second elements (12.2, to 12.n) may also be similar to one another. For exemplary purposes, a first element is designated by the reference numeral (12.1) and a second element by the reference numeral (12.2) in the drawings. The second element (12.2) defines an aperture therein, or at least one aperture therein, presently four slotted apertures (20) or slots. The first element (12.1) may also have one or more slots (24) therein, presently three slots (24), as will be described in more detail below. The earth cutting apparatus (10) may further include a plurality of earth cutting hooks (26, 28). Two types of earth cutting hooks are used in the present embodiment, a two-clawed earth cutting hook (26) and a three-clawed earth cutting hook (28). However, it will be appreciated that many other arrangements are possible including earth cutting hooks that each have a single claw or hooked portion. It may also be possible to use a single type of earth cutting hook for a band of articulated elements, instead of using different types of earth cutting hooks on the band (14). Examples of the two-clawed earth cutting hook (26) and the three-clawed earth cutting hook (28) are depicted in Figures 3 and 4. The two, and three-clawed embodiments of the earth cutting hooks (26, 28) may be similar, apart from the number of claws and an overall width of the earth cutting hook may be different, depending on the number of hooks or claws. Referring to Figures 1 and 3, each earth cutting hook (26) may include a proximal end (30) which can be affixed to the first element (12.1), and an earth cutting end (32) shaped so as to be capable of slidably extending through the aperture (20) of the second element (12.2), so as to be moveable between a retracted position (34) and an extended position (36), for example as shown in the side view in Figure 2. The retracted position may also be referred to as a withdrawn position or a partially withdrawn position or an inoperative position, whereas the extended position may also be referred to as a partially extended position or an operative position or an earth engaging position of the earth cutting hook. In the partially extended position, and while moving from the partially withdrawn position to the partially extended position, the earth cutting end of the earth cutting hook may perform a clawing motion, as will be described in further detail below. Still referring to Figure 2, in use, the band (14) of articulated elements may be rotated or moved by the driver wheel (18) around the idler wheel (16). The driver wheel (18) is presently in the form of a cog or a sprocket, but it will be understood that other arrangements are possible. The driver and idler wheels may also be reversed in position in some embodiments. One or more chains (15) (see Figure 1) may be rotatable by the driver wheel (18) and a plurality of driver wheels or sprockets may be used as required. In the present embodiment, the articulated band (14) of elements may be rotatable with the one or more chains (15) by the driver wheel(s) (18) or drive sprockets, around the idler wheel(s) (16) or roller(s). One or more idler wheels may be implemented if necessary. During rotation of the articulated band (14) of elements, hinged movement of the second element (12.2) relative to the first element (12.1) in a first direction may cause the earth cutting end (32) of the earth cutting hook (26) to slidably extend from the second element (12.2) to the extended position (36) for operatively cutting earth. In the present embodiment, hinged movement of the second element (12.2) in an opposite direction causes the earth cutting hook (26) to slidably retract to the retracted position (34). For example, when the articulated band (14) of elements is rotated around the idler wheel (16), the second element (12.2) moves hingedly or pivots through an angle (α) relative to the first element (12.1), in the first direction (i.e., away from planar alignment of the elements). This relative movement may, in turn, cause the earth cutting hook to slidably extend from the second element (12.2) to the extended position (36). When the band (14) is rotated further, hinged movement in an opposite direction may occur (i.e., in a direction toward planar alignment of the elements), and the second element (12.2) may move so as to be closer into line with a plane of the first element (12.1) (i.e., decreasing the angle (α) between the elements), and this may cause the earth cutting hook (26) to retract again to its retracted position (34). Referring to Figures 3 and 4, the two-clawed earth cutting hook (26) may have a hooked portion (38) near its earth cutting end (32). The three-clawed earth cutting hook (28) may also have a hooked portion (40) near an earth cutting end (42) thereof. Like the two-clawed embodiment (26), the three-clawed embodiment (28) may also include a proximal end (44). The earth cutting ends (32, 42) may also be referred to as earth engaging ends. Each earth cutting hook (26, 28) may include a plurality of hooked portions (38, 40), claws or teeth near the earth cutting end (32,42) of the earth cutting hook (26, 28). For example, each earth cutting hook may include two hooked portions or claws (see Figure 3), or three hooked portions or claws (see Figure 4), or more than three hooked portions or claws (not shown). The hooked portions (38, 40) may be angled, or may have a claw-like shape terminating in an earth cutting tip (46, 48). The earth cutting tip (46) may optionally be sharpened, and the earth cutting ends (32, 42) may also be sharpened. The earth cutting hooks (26, 28) or portions thereof may preferably be made from a strong tough material, such as a metal, alloy, steel, tungsten, titanium, or the like, composites or ceramics, and the earth cutting hooks may be hardened. The earth cutting hooks may additionally or alternatively include diamond bits or diamond tips in some embodiments. Alloys or compound materials (e.g. tungsten carbide) may also be used to manufacture the earth cutting hooks or portions of each hook. As described herein, embodiments wherein the earth cutting hook includes one, two, three or more than three hooked portions may be possible. These hooked portions (38, 40) may also be referred to as claws or teeth or prongs of the earth cutting hooks (26, 28). The earth cutting hooks or claws (26, 28) may be relatively simple and inexpensive to manufacture and once fastened to the plates (12.1, 12.2 as the case may be), the claws may be rigid, tough and strong. A second moment of inertia of the claw or hook (26, 28) may also be in line with a plane of each hooked portion (38, 40) and in line with a digging motion (64, see Figure 1) of the earth cutting apparatus (10) and the earth cutting system (100). This may cause the earth cutting hooks (26, 28) to be stiff and strong, or it may enable them to resist fatigue and/or mechanical failure. It may also be advantageous that the earth cutting hooks themselves (26, 28) do not have any moving parts, i.e. reducing the likelihood of components of the system failing or jamming. The angled or curved shape of the earth cutting hooks may also facilitate the clawing motion by which soil is worked during use, so as to facilitate deep soil working. Each earth cutting hook (26, 28) may include a mounting plate (50, 52) near its proximal end (30, 44), so as to enable the proximal end (30, 44) of the earth cutting hook (26, 28) to be affixed to the first element (12.1) by way of the mounting plate (50, 52). In the case of the three-clawed embodiment (28), its mounting plate (52) may be affixed to the second element (12.2) as will be described in more detail below. However, it will be appreciated that any one of the types of earth cutting hooks may be affixed to any one of the first and second elements (12.1, 12.2) as required by the particular application. The mounting plate (50, 52) may for example include one or more holes (54, 58) therein, for attaching the mounting plate (50, 52) to the first or second element (12.1, 12.2) as the case may be. Any type of fastener may be used, such as bolts and nuts, screws, rivets; or the mounting plate may be affixed to the first or second element in another way. For example, the mounting plate may be affixed by welding, or it may be held by a retaining structure of the first or second element (e.g. a slotted formation or bracket), or the earth cutting hook may even be integrally formed with the first or second element (12.1, 12.2) with the earth cutting ends (32, 42) extending away from the relevant element (12.1, 12.2, as the case may be). The hooked portions (38, 40) of each cutting hook (26, 28) may be generally planar. This may be advantageous, because the planar earth cutting hook may be strong or rigid in the plane in or along which it extends. As seen in Figures 3 and 4, the mounting plate (50, 52) may be transverse to a plane of the earth cutting hook (26, 28), or the mounting plate (50, 52) may be transverse to a plane of the hooked portion (38, 40). In other words, the mounting plate may be positioned transversely or across a major plane along which a length of a body of the earth cutting hook may extend in use, with the length taken from the proximal end toward the earth cutting end. One or more reinforcing members (60, 62) or cross-beams may be provided so as to strengthen a body the earth cutting hooks (26, 28). Moreover, the first element (12.1) may also be referred to as a leading element or a leading plate, while the second element (12.2) may be referred to as a trailing element or a trailing plate. The first and second elements (12.1, 12.2) may be referred to as grouser plates. Referring to Figures 1 to 4, the earth cutting apparatus (10) may include a plurality of earth cutting hooks (26, 28). The plurality of earth cutting hooks (26, 28) may be provided on the articulated band (14) of elements. The earth cutting hooks (26, 28) may be configured to move between their extended (36) and retracted (34) positions as the articulated band (14) of elements moves around the driver (18) and idler (16) wheels in use. The extended (36) and retracted (34) positions for the two-clawed earth cutting hook (26) is shown in Figure 2, and it should be understood that the three-clawed earth cutting hook (28) may also be moveable between a retracted position (65) and an extended position (67) in a similar way. The three-clawed earth cutting hook (28) is shown in its extended position (67) on the right hand side of the idler wheel (16) in Figure 2, and its retracted position (65) is also shown for a portion of the articulated band (14) of elements that may be substantially in line or substantially straight, in other words, while moving or travelling to and from the driver wheel (18) (i.e. between the driver and idler wheels (18, 16)). In the present embodiment, the band (14) of elements may be rotated in an anticlockwise direction as illustrated by the directional arrow (64). However, embodiments that utilise rotation in another direction may also be possible. In use, the idler wheel (16) and a portion of the band (14) of elements may be lowered beneath a surface (68) of the earth. Each earth cutting hook (26, 28) may be configured to perform a clawing motion as it moves from the retracted position (34, 65) to the extended position (36, 67), for example while moving or rotating around the idler wheel (16). This may enable the one or more earth cutting hooks (26, 28) to pierce and/or cut and/or rip earth or soil in use. An example of the earth cutting system in use is also shown in Figure 10 which is described in more detail below. Referring again to Figure 1, the earth cutting hooks (26, 28) may be arranged in one or more rows along the articulated band (14) of elements. In the present embodiment three rows (70.1, 70.2, 70.3) are provided, as are diagrammatically indicated by broken lines, and each row may include sixteen earth cutting hooks (26, 28 as the case may be), but other numbers of earth cutting hooks or elements may also be possible. Presently the first and third row (70.1, 70.3) include two-clawed earth cutting hooks (26) while the second row (70.2) includes three-clawed earth cutting hooks (28). It will be appreciated that many other arrangements are possible. In the present embodiment, the earth cutting hooks (26, 28) are arranged in parallel rows (70.1, 70.2, 70.3) along the articulated band (14) of elements. The earth cutting hooks (28) in the second row (70.2) may be staggered relative to the earth cutting hooks (26) in the first row (70.1). Hence, the earth cutting hooks (26, 28) may be arranged in a staggered formation along the articulated band (14) of elements. This staggered formation may enable efficient earth cutting and may inhibit earth, mud or other material to become stuck to the band (14) of elements, or in-between the earth cutting hooks (26, 28). The staggered formation may also facilitate repetitive earth cutting, for example with a middle earth cutting hook (28) performing a first pierce or cut of the earth, followed by one or more further earth cutting hooks (26) that successively pierce or cut earth at an adjacent or parallel location as the band (14) of articulated elements is rotated. Successive cuts, piercing or penetration of the earth may be performed in a triangular or staggered way. The first and second rows (70.1, 70.2) (and/or further rows) may be adjacent to one another, and the earth cutting hooks (26) in the first row (70.1) may be spaced, with the earth cutting hooks (28) in the adjacent second row (70.2) at least partially interposed between the earth cutting hooks (26) in the first row (70.1). The staggered formation may enable efficient soil fail zones in front of the apparatus (10), which may be particularly advantageous in deep soil working applications. One or more chains (15) may be provided for the articulated band (14) of elements or plates, and presently a first chain (15) driven by the driver wheel or sprocket (18) may be provided for the first row (70.1) and the elements (12.1, 12.2) may be affixed to the chain (15). Further chains and sprockets or driver wheels for further rows (70.2, 70.3…) may also be provided. The driver wheel may be mounted on a shaft, driveshaft or axle which may be rotatable by a power source. Alternatively, the plates or articulated elements (12.1, 12.2) may themselves form part of the chain (15) or series of links. In the extended position (36, 67) of each earth cutting hook (26, 28), the one or more hooked portions (38, 40) may, in use, at least partially extend through one or more apertures (20) or slots of the second element (12.2), so as to be capable of cutting earth. As shown in Figure 1, each first element (12.1) may also include one or more apertures (24) therein, for one or more further earth cutting hooks (28) to at least partially extend through (presently the three-clawed earth cutting hooks (28) extend through these apertures (24)). In the case of the earth cutting hooks being arranged in one or more rows (70.1, 70.2, 70.3) along the articulated band of elements, a middle row or second row (70.2) of earth cutting hooks (28) may include the three-clawed earth cutting hooks (28) that may be affixed to second elements (12.2) to form the staggered formation with the earth cutting hooks (26) in the first and/or third rows (70.1, 70.3) (presently the two- clawed earth cutting hooks (26)). These earth cutting hooks (28) in the second row (70.2) may at least partially extend through the apertures (24) in each of the first elements (12.1). The apparatus (10) may have a width (W) and the apertures (20, 24) and corresponding earth cutting hooks (26, 28) of the plurality of first and second elements (12.1, 12.2) may be arranged along the width (W) of each element (12.1, 12.2). The aperture (20, 24) in the first and/or second elements (12.1, 12.2) may be sized and shaped to accommodate the hooked portion (38, 40) of the earth cutting hook (26, 28 as the case may be) therethrough. For example, the aperture(s) in the first and/or second elements may each be shaped as a slot. The slot(s) may be sized to slidably accommodate the earth cutting end (32, 42) of each earth cutting hook (26, 28) therethrough. Presently, the apertures (20, 24) are slotted so as to be capable of receiving the generally planar hooked portions (38, 40) therethrough, as shown in Figure 1. However, other shapes of apertures may also be used, for example if the hooked portions are differently shaped, for example rounded, square, oval, triangular or any other cross-sectional shape of the hooked portions of the earth cutting hooks and their corresponding apertures in the first and/or second elements. The one or more apertures (20, 24) in the first (12.1) and/or second (12.2) elements may be arranged to clean or to perform self-cleaning of the earth cutting hooks (26, 28) as they retract or move from the extended position (36, 67) to the retracted position (34, 65). This cleaning process may be performed automatically. For example, while the band (14) of articulated elements is moving or rotating about the idler wheel (16), in particular when the band moves from a tangential position in relation to the idler wheel (16) and towards the driver wheel (18), this may cause the elements (12.1, 12.2) to straighten out relative to one another which, in turn, may cause retraction of the earth cutting hooks (26, 28) or at least partial retraction of the earth cutting ends (32, 42) back into the apertures (20, 24) which may cause earth, mud or other material to simply fall off. Edges of the aperture(s) (20, 24) may be arranged to scrape the earth cutting hooks (26, 28) as they retract or move from the extended position (36, 67) to the retracted position (34, 65), thereby causing earth, mud or other material to be dislodged from the hooked portions (38, 40) of the earth cutting hooks (26, 28). Each of the first and second articulated elements (12.1, 12.2) may include one or more earth cutting hooks affixed thereto, for example along the width (W) of each element (12.1, 12.2). In the present embodiment, the first element (12.1) has two earth cutting hooks (26) affixed thereto, by way of the mounting plates (50) as can be seen and understood from the three-dimensional view in Figure 1. In other words, the first element (12.1) may have an earth cutting hook (26) in the first row (70.1) and an earth cutting hook (26) in the third row (70.3) affixed to the element (12.1) spaced along its width (W). Successive earth cutting hooks (26) in the band (14) may also be spaced. In the present embodiment, each second element (12.2) has a single earth cutting hook (28) (presently the three-clawed embodiment) mounted near a middle of the width (W) of the second element (12.2) by way of the mounting plate (52). Each of the first and second elements (12.1, 12.2) may include one or more apertures for further earth cutting hooks to extend through. Presently, the second elements (12.2) include apertures (20) for receiving earth cutting hooks (26) mounted to first elements (12.1), whereas the first elements (12.1) include apertures (24) for receiving earth cutting hooks (28) mounted to second elements (12.2). It will be appreciated that many other arrangements or configurations are possible. In the present embodiment of the earth cutting apparatus (10), the one or more earth cutting hooks (26, 28) may be affixed to a radially inner surface of the first and/or second elements (12.1, 12.2). The tips (46, 48) and earth cutting ends (32, 42) or hooked portions (38, 40) may, at least partially, extend radially outwardly from a radially outer surface of the first and/or second elements (12.1, 12.2) through the apertures (20, 24), in particular when in their extended positions. Preferably, the hooked portions (38, 40) or the earth cutting ends (32, 42) of each of the earth cutting hooks (26, 28) may be arranged to extend radially outwardly from the first and/or second elements (12.1, 12.2) as they move between their retracted (34, 65) and extended (36, 67) positions while the articulated band (14) of elements is, in use, rotated around the driver (18) and idler (16) wheels. Each of the hooked portions (38, 40) may be generally planar, and the hooked portions may extend in a major plane, like prongs of a fork or claw. The generally planar configuration may provide mechanical strength and rigidity, which may be advantageous as it resists wear or mechanical failure. In particular, the planar configuration may provide mechanical strength in a direction along the major plane of each hooked portion, claw or prong. An earth cutting system (100) is also disclosed. The earth cutting system may include one or more features of the earth cutting apparatus (10) as described herein. For example, the system (100) may include the band (14) of articulated elements including at least the first element (12.1) or plate and the second element (12.2) or plate hingedly connected to the first element (12.1). The second element (12.2) may define the aperture (20) therein, and the band (14) of articulated elements (12.1, 12.2) may be provided around the idler wheel (16) and the driver wheel (18) for rotating the band of elements in use. The system (100) may include at least one earth cutting hook (26) including the proximal end (30) which may be affixed to the first element (12.1) and an earth cutting end (32) capable of slidably extending through the aperture (20) of the second element so as to be moveable between a retracted position (34) and an extended position (36), such that when the band (14) of articulated elements is rotated, the earth cutting hook moves to the extended position (36) when the earth cutting hook (26) is at a first location (72) relative to the idler wheel (16) for operatively cutting earth, and moves to the retracted position (34) when the earth cutting hook (26) is at a second location (74) relative to the idler wheel. The earth cutting hook may move to the retracted position (34) as result of the elements (12.1, 12.2) straightening out or substantially aligning with one another as can be seen in Figure 1. This may cause the earth cutting ends (38) to slidably retract into the apertures (20). It will be appreciated that the system (100) may include features of the earth cutting apparatus (10) including the two clawed earth cutting hooks (26) as well as the three-clawed earth cutting hooks (28), or earth cutting hooks with single hooked portions may be used in the system (100). The system may also include a motor or power source (not shown) for driving the driver wheel (18). Referring to Figure 2, each earth cutting hook may remain stationary in relation to the element to which it is mounted, while moving relative to an adjacent element. This may be explained with reference to the two-clawed earth cutting hook (26), but it may be equally applicable to the three- clawed embodiment, or a single clawed earth cutting hook (not depicted). The proximal end (30) of the earth cutting hook (26) may be affixed to the first element (12.1) and rotate together therewith around the driver and idler wheels (18, 16). When the first element approaches the idler wheel (16) (or driver wheel for that matter), the second element (12.2) may pivot, or hingedly move relative to the first element (12.1) as indicated by the angle (α), and this may cause the earth cutting hook (in particular its tip and hooked portion) to at least partially extend from the second element (12.2) through the slot or aperture (20). This may cause the tip(s) (46) and earth cutting end (32) of the earth cutting hook to dig or claw into the earth or ground, causing a clawing motion, or a clawing action, and the earth cutting hook may pierce, cut, rip, or tear apart the earth, for example for agricultural purposes or the like. When the first element (12.1) then continues to rotate about the idler wheel, earth may be cut further and eventually when the earth cutting hook withdraws or partially retracts to the retracted position (34), earth, mud, or other material may simply fall off (by the edges of the apertures performing scraping as described herein) which may provide an efficient means of working the earth. The earth cutting hooks (26, 28) may have the advantage of being structurally secure or having structural strength, because they are affixed to the first or second elements (12.1, 12.2). The earth cutting hooks (26, 28 as the case may be) may also be of relatively simple construction because they may remain stationary relative to one of the first and second elements (12.1, 12.2, as the case may be) during rotation. It may be advantageous to have less components than with known systems or apparatuses, and the present disclosure may be capable of providing at least equal or better earth working capabilities than with known devices or systems at a reduced manufacturing cost, or with simpler manufacturing techniques (e.g. because the earth cutting hooks (26, 28) are simply mounted to, fastened to, permanently fastened to, or form part of to the relevant elements (12.1, 12.2)). It will further be appreciated that the first and second elements may be reversed and either of the first and second elements may include one or more features of the other of the first and second elements. The arrangement or number of earth cutting hooks may also be changed, and the earth cutting hooks may be mounted to, or may extend through any one of the first and second elements. Embodiments may also be possible wherein the earth cutting hooks are at least partially mounted to a radially outer surface of the elements. Still referring to Figure 2, the claws or earth cutting hooks (26, 28) may utilise the angular displacement (α) of the leading plate (12.1) relative to the adjacent, trailing plate (12.2) to facilitate deeper penetration of the cutting tips (46, 48) of the earth cutting hooks (26, 28) into the soil as well as cleaning of the earth cutting hooks when they move to their withdrawn or retracted positions, e.g. as they rotate around the idler wheel (16) or roller. The earth cutting hooks may be sickle-shaped or curved. The earth cutting apparatus (10) and system (100) may optionally include a frame (76) or structure which may be arranged to mount the earth cutting apparatus (10) or system (100) to a vehicle, such as an agricultural or earth working vehicle. Hydraulics, pneumatics or another moving mechanism may be provided to lower or raise the earth cutting apparatus (10) or system (100) to work the earth or soil. The apparatus (10) or system (100) may for example be lowered approximately into the orientation shown in Figure 2 for working or cutting earth. The sprocket or driver wheel (18) may be operatively connected to a drive shaft and power source, such as an internal combustion engine, a hydraulic or pneumatic system or an electric motor (not shown) for driving the driver wheel (18) in use. An elongate beam (77) may be provided between the driver and idler wheels to provide structural stability. One or more bearings may also be provided for the chain (15), driver and idler wheels (18, 16), or other components of the apparatus (10) or system (100), so as to reduce mechanical friction or wear. The chain (15) and a substantial portion of the earth cutting hooks (26, 28) may be located radially inwardly of the articulated elements (12.1, 12.2) or plates. This may provide the advantage that these components may be protected from excessive mechanical wear due to the ground or earth being generally located radially outside of the articulated elements (12.1, 12.2) or plates in use. The articulated elements or plates may hence serve as a barrier or shield to keep earth, mud or other material outside the other radially inner components of the apparatus (10) and system (100), such as the chain, the driver and idler wheels, bearings, and the earth cutting hooks themselves (in particular when they are retracted). This may reduce mechanical wear, and may also facilitate ease of maintenance, or reduce the frequency of required maintenance, also in conjunction with the self-cleaning features of the hooks and apertures as described herein. The earth cutting apparatus, system and method described herein may also require less drafting power or less draft, pushing or pulling force, or less rotational power (e.g. to the driver wheel) than are required for known devices, systems, or methods. The reduced draft, pushing or pulling force may be achieved by way of the clawing motion or clawing action of the earth cutting hooks, and/or due to the self-cleaning features of the apertures, and/or due to the barrier that the elements create between the earth and the remainder of the components of the apparatus or system. The present disclosure may further provide the advantage that a three-dimensional soil-zone failing in front of the earth cutting hook as well as at its sides may be cut, or separated more effectively due to the clawing motion of the earth cutting hooks and the staggered formation of earth cutting hooks used. The present disclosure may for example enable earth cutting or earth working at a depth of 600 mm or more, however, significantly larger or smaller depths may be possible, depending on the particular arrangement of the earth cutting hooks and other components of the apparatus and system. The present disclosure may enable working earth at depths where a reduction in soil disturbance with an increase in soil compaction would normally have been encountered and may facilitate earth to be worked more efficiently than with known devices or systems. The present disclosure may enable tilling or working of earth at relatively large depths (e.g. more than 500mm), and the present disclosure may require less energy input required for tilling compared to known systems. The present disclosure may also facilitate earth working to promote the growth of plant roots particularly at low moisture levels, and may enable enhanced water penetration and may increase moisture retention capacity of the soil. Moreover, the present disclosure may enable an increase in void spaces in the worked earth for holding adequate water-air-nutrient mixtures as well as facilitating an increase in the magnitude of soil pore sizes which may aid crops to receive water and nutrients. These and other advantages may be provided due to the clawing action and deep soil working capabilities of the present disclosure. This may facilitate crops to receive water and nutrients more efficiently than with known apparatuses, systems or methods. The present disclosure extends to an earth cutting method. An exemplary earth cutting method (1000) is shown in the high-level flow diagram in Figure 5. The earth cutting method (1000) may include implementing one or more features of the earth cutting apparatus (10) and system (100) as described herein. The earth cutting method (1000) may include rotating (1010) a band (14) of articulated elements (12.1, 12.2) by a driver wheel (18) around an idler wheel (16), the band (14) of articulated elements (12.1, 12.2) including at least a first element (12.1) and a second element (12.2) hingedly connected to the first element (12.1), the second element (12.2) defining an aperture (20) therein. The method (1000) may further include utilising (1012) at least one earth cutting hook (26) including a proximal end (30) which is affixed to the first element (12.1) and an earth cutting end (32) capable of slidably extending through the aperture (20) of the second element (12.2) so as to be moveable between a retracted position (34) and an extended position (36). As mentioned before, the earth cutting hooks may be affixed to either of, or both of the first and second elements. The earth cutting hooks may also extend through apertures in either of, or both of the first and second elements, depending on the particular application. Any features of either of the first or second elements, or any features of the different types of earth cutting hooks may provided by one or more of the other elements or earth cutting hooks. The method (1000) may further include driving (1014) the driver wheel (18) to operatively rotate the band (14) of articulated elements (12.1, 12.2) around the idler wheel (16) such that during rotation of the band (14) of articulated elements (12.1, 12.2), the earth cutting hook (26) moves to the extended position (36) when the earth cutting hook is at a first location (72) relative to the idler wheel (16) for operatively cutting earth, and moves to the retracted position (34) when the earth cutting hook is at a second location (74) relative to the idler wheel (16). In Figures 6 and 7 are shown exemplary embodiments of articulated elements (12.1, 12.2) or plates with their earth cutting hooks (26, 28) that may be used in the exemplary system (100) of Figure 1 as described herein. In Figure 6, two-clawed earth cutting hooks (26), and a three-clawed earth cutting hook (28) are shown. Figure 6 also shows links of the chain (15) in more detail. In the exemplary embodiment, two chains (15) may be used (or a plurality of chains), and they may be rotatable by the driver wheel (18) or sprocket (see Figure 1). The driver wheel (18) may include a plurality of sprockets spaced to rotate the plurality of chains (15). The chains may be attached to one or more of the articulated elements (12.1, 12.2), so as to enable the elements to be moved by the driver wheel as it engages the chains. In the exemplary embodiment shown in Figure 6, the earth cutting hooks (26, 28) may be manufactured by a process such as laser-cutting, and the claws may then be bent into the shape shown and/or parts of each hook may be bolted or attached together. In the present embodiment, the earth cutting hooks may be manufactured without the use of welding, and this may facilitate manufacturing to be less expensive and/or less complex. Figure 7 shows an alternative arrangement of earth cutting hooks having hooked portions (39) that are beak-shaped. It will be appreciated that the earth cutting hooks shown in Figures 3 and 4 may also be used, depending on the particular application. In Figure 7 the chain is omitted for the sake of clarity. The grouser plates or elements (12.1, 12.2) may also include angled portions (19) which may be arranged to scoop earth or soil as the band of elements is rotated. It will be appreciated that any of the articulated elements or plates described herein may include these angled portions. The angled portions (19) may also be referred to as scoops. Figures 8-10 show an exemplary embodiment of an earth cutting unit (2000). The earth cutting unit (2000) may include a skid or skid plate (2010) and it may be arranged to be drawn, pushed or pulled by a vehicle (2020) such as a tracked vehicle. The embodiment shown is arranged to be drawn. Embodiments may also be possible wherein the earth cutting unit (2000) may form part of the vehicle. The earth cutting unit (2000) may include one or more earth cutting system(s) (200). In the embodiment shown, the earth cutting unit includes four earth cutting systems (200), with two earth cutting systems (200) on each side of the skid (2010). One or more shroud(s) (2029) or cover(s) may also be provided to at least partially enclose each earth cutting system (200). Raising and lowering members (2012) such as hydraulic cylinders may be provided to raise and/or lower the earth cutting systems (200) of the earth cutting unit (2000) to work or cut earth. These may also be referred to as depth control cylinders (2012). Referring to Figure 10, a lowered position of the earth cutting system(s) (200) is diagrammatically illustrated, while a raised position (or a stowed position or a retracted position) is shown in Figures 8-9. Each of the earth cutting systems (200) may be similar to the earth cutting system (100) described above, and each earth cutting system (200) may include an earth cutting apparatus (10) and earth cutting hooks as described herein. Each earth cutting system (200) may also include a plurality of articulated elements as described above. The articulated elements may be articulated plates and form part of an articulated band of plates or elements that may be rotatable around a driver wheel (218) and an idler wheel (216). The driver wheel (218) or sprocket may be mounted on a drive shaft and it may be rotatable by one or more power sources, such as electric motors (2023). It will be appreciated that other types of motors or driving arrangements may be possible. For each earth cutting system (200), the driver wheel (218) may be driven by a geared, belt-driven, or chain- driven drive system (2025) or driving arrangement which may be arranged to deliver power from the power source (2023) to the driver wheel (218). The drive system (2025) may also be referred to as a speed reducer. A drive system (2025) may be provided for each earth cutting system, or for each pair of earth cutting systems (200), or a single drive system (2025) may be used to drive the earth cutting systems (200) simultaneously (e.g., to drive all four earth cutting systems (200) in Figure 8). However, embodiments may be possible wherein each earth cutting system (200) may be driven individually. The drive system (2025) may include a housing or enclosure, and optionally the skid (2010) may form part of a bottom of this enclosure or housing. The housing or enclosure may inhibit soil or other material from entering an interior thereof. A two-stage chain reduction may be used in the drive system (2025) to deliver power from the motor(s) (2023) to the driver wheel(s) (218). A chain drive arrangement may be preferred due to the shock absorbing properties of chains as opposed to geared arrangements, because chains are able to flex or stretch to an extent. This may be useful because of the high loads required when working or cutting earth or soil. Maintenance of a chain drive arrangement or chain drive system may also be easier than with a geared drive arrangement. The chain drive system (2025) is not shown in the drawings, but it will be appreciated that it may be contained inside the enclosure or housing. Even though mechanical or internal combustion motors, or other types of motors may be used, it may be advantageous to use electric motor(s) (2023), due to their accurate speed control and their ability to deliver relatively high torque at a lower RPM via the chain drive system (2025). It will further be appreciated that the present embodiment in Figures 8-10 may include one or more features of the other embodiments described herein, or one or more of the other embodiments described may include one or more features of the present embodiment. The skid (2010) may also be referred to as a wear plate, and it may be replaceable. The chain drive system (2025) may also include one or more tensioners for tensioning the two-stage chain reduction. Another exemplary embodiment of an earth cutting unit (3000) is shown in Figure 11. In this embodiment, a pair of earth cutting systems (200) are provided toward one side of a skid (3010). Further features of the present embodiment may be similar to the embodiment described with reference to Figures 8-10. The earth cutting unit (3000) may also be drawn, pushed or pulled by a vehicle such as the vehicle (2020) shown in Figure 10. Other vehicles or tractors may also be used. It will be appreciated that the present embodiment in Figure 11 may include one or more features of the other embodiments described herein, or one or more of the other embodiments described may include one or more features of the present embodiment. The embodiments described herein may provide the advantage that the overall earth cutting system may be relatively narrow. This may find particular application in agriculture, for example where soil working is required in vineyards or the like, where limited space is available. The embodiment shown in Figure 11 may also be used when only one side of the skid needs to be worked (e.g. when the other side has established vineyards, orchards, crops or the like that a farmer desires to keep in tact). On the other hand, the embodiment shown in Figures 8-10 may find application in open fields where both sides of the skid may require to be worked simultaneously. It is further envisaged that the apparatus, system and method of the present disclosure may facilitate deep working of earth or soil for preparation and treatment of the soil or earth. Soil ameliorants, fertiliser, carbon or the like may be introduced at a variety of depths, for example beyond the critical depth of about 600mm. Aspects of the present disclosure may also provide an apparatus system or method for sequestrating or introducing carbon into the earth. In other words, carbon may be buried below ground by working the ground by the apparatuses, systems or methods described herein, and subsequently or simultaneously introducing the carbon below ground and burying it. This may provide a useful means of integrating or re-integrating carbon deeper into the soil than would otherwise have been possible, or it may provide a carbon sink and/or a long-term carbon storage means. Many types of carbon-based materials may be introduced into the soil, which not only improves soil quality but also enables the disposal or re- purposing of carbon or waste carbon. Deep integration or sequestration of carbon (or carbon- based or carbon containing) material into the earth may facilitate micro-organism growth and/or it may create an advantageous environment for organisms that are helpful to soil “health” or quality. This may, in turn, improve the overall quality and sustainability of the soil worked or rehabilitate soil. Biochar is one example of a carbon-based material that may be buried or integrated into the soil by implementation of the present disclosure. However, it will be appreciated that many other types of substances, fertilisers, ameliorants or materials may be integrated into the soil, depending on the particular application. The foregoing description has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure. The language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims. Finally, throughout the specification and accompanying claims, unless the context requires otherwise, the word ‘comprise’ or variations such as ‘comprises’ or ‘comprising’ will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.