Sinomenium cantalense was an early Eocene member of the moonseed family known from its hard fruit stone. The family is dominated today by climbing plants, so a climbing growth habit is plausible, but no attached London Clay stems or leaves demonstrate the form of the parent plant directly.

The endocarp protected a single seed and carried a series of transverse ridges around its outer surface. Modern morphometric work has shown that several historical fossil names fall within the variation of this species, making the shape of the fruit stone and the number of ridges more useful than old specimen labels.