This bivalve, Modiolus, is very similar to the modern-day mussel. Like today’s mussels, they probably formed colonies, often partly burying themselves in mud, and filtering the water for food. They in turn would have been food for crabs and starfish.
As the name suggests, bivalves consist of two shells. ‘Bi’ means two and ‘valve’ means shell. The shells are held together by a strong muscle, and hinged at the pointed end. If you’ve eaten scallops, you’ll know how strong the muscles are!
Find out more about bivalves on the molluscs pages.