A burrowing mollusc is a type of mollusc that lives in the ground, usually in sandy or muddy areas. The most common example of this type of mollusc is the CLAM, which is a four-letter word that can be used to describe this creature. Clams are bivalve molluscs, meaning they have two shells that are connected by a hinge. They feed by filtering water and extracting nutrients from it. Clams are found in many different habitats, including oceans, rivers, and lakes.