Like oysters and mussels, clams are bivalves, a kind of mollusk that's encased in a shell made of two valves, or hinging parts. And that shell comes in all different sizes. There are small clams ...

"This ancestor probably had a hard shell, a foot for movement ... The study has confirmed that the evolutionary lineage of ...

All mollusks build their own shells, whether they live in water or on land. Creatures like snails, clams, oysters and mussels use an organ called a mantle to secrete layers of calcium carbonate ...