These bivalves are
epifaunal byssate suspension feeders of up to 12 cm in size. The shells are obliquely ovate, moderately inflated, with obtuse posterior and smaller anterior wings.
Plagiostoma giganteum is a well-known fossil bivalve which occurs in the
Blue Lias formation in various parts of the
United Kingdom, although it is geographically widespread and has also been found in the Triassic of the United Kingdom. ==Gallery==