To provide a seal or seal assembly having two independently-operable opening/closing lids which make it possible to gain access to the inside of a container in order to take out a small quantity of contents according to the properties of the contents.

An opening/closing base 24 which can be attached to a container has two ports 36 and 38 which are separately and selectively sealed and opened by lids 58 and 60, respectively, situated above them. The ports 36 and 38 have discharging zones 44 and 48, respectively, which are free of blockage, and the lids 58 and 60 have upper surfaces which are in the same plane. Further, positioning ears 66 and 68, which are integrated, are provided for elastically holding the corresponding lids both in closing positions and opening positions.