The Unionidae are a family of freshwater mussels, the largest in the order Unionida, the bivalve molluscs sometimes known as river mussels, or simply as unionids.
Unionidae
Freshwater bivalves are one kind of freshwater mollusc, along with freshwater snails. They are bivalves that live in fresh water as opposed to salt water, which is the main habitat type for bivalves.
Family Margaritiferidae, a shell of Margaritifera auricularia
Family Unionidae, Quadrula metanevra, the monkeyface mussel
Family Unionidae, Anodonta cygnea
Family Corbiculidae, shell of Corbicula fluminea