A clam is a type of bivalve mollusk that lives in both freshwater and saltwater environments. Clams have two hinged shells that protect their soft bodies. They are known for their ability to burrow into the sand or mud, where they filter feed on plankton and other small particles in the water. Clams are an important part of many ecosystems and serve as a food source for various animals, including seabirds and fish. They are also harvested by humans for food, with popular varieties including littleneck clams and cherrystone clams, often enjoyed in dishes like clam chowder.