Mollusks Fossil Collection
Clams have a long fossil history, first appearing in the late Cambrian Period, about 510 million years ago. Clams are bivalve mollusks, so-called because their shells consist of two parts called valves. The valves are attached by a hinge ligament and are opened and closed by two muscles attached to the inside of the shells. Clams are filter feeders that pump water inside their bodies to strain out phytoplankton and other small organisms for food.