Clam

Clam is a common name for several species of bivalve mollusc, most often applied to edible varieties that live as infauna, spending most of their lives half buried in the sand of the sea floor or a riverbed. Clams have two shells of equal size joined near a hinge by a flexible ligament and connected by two adductor muscles, and they burrow with a powerful foot, feeding as filter feeders in both fresh water and marine environments, with the greatest diversity found in North America. Culinary clams differ from related shellfish in that they do not attach to a surface the way oysters and mussels do, nor do they live on the ocean bottom like scallops, and common edible varieties include rounded or triangular species such as palourde clams as well as elongated razor clams, whose shape suggests an old fashioned straight razor. Lifespan varies greatly among clam species: some live only a year, while at least one specimen has been found to be more than 500 years old.