Bivalves are also known as "hatchet foot" because they use their foot for burrowing the sand. 

Bivalves including clams, oysters, mussels, and scallops have two shells hinged together.  The word bivalve means "two leaf".

Bivalves are carnivorous and are bilaterally symmetrical.  Most are sedentary and live in mud and sand in marine and fresh water habitat.