Other common names are rock oyster, jungle shell,jingle shell, and pearly Monia. The size is usually about 13cm long. They're usually attached to solid objects. (The beachcombers guide to seashore life in the Pacific Northwest)
Several small individuals.
Bivalvia is a class of marine and freshwater molluscs with laterally compressed bodies enclosed by a shell in two hinged parts. Bivalves include clams, oysters, mussels, scallops, and numerous other families of shells. The majority are filter feeders and have no head or radula. The gills have evolved into ctenidia, specialised organs for feeding and breathing. Most bivalves bury themselves in sediment on the seabed, where they are safe from predation. Others lie on the sea...