Bivalve mollusks include cockles, scallops, razor shells, oysters, mussels, and clams. The bivalves often resemble fossil brachiopods or spirifers but closer inspection reveals important differences. Most bivalves have shells composed of two parts or valves. Often these shells were hinged; the two shells were held shut by interior muscles on the creature. Most bivalves were marine dwellers, but some lived in lakes and rivers.
Clam
Clam
