Which invertebrate group contains soft bodied animals that live in a hard shell?

Mollusks are a diverse group of invertebrates that includes animals such as snails, clams, octopuses, and squids. Mollusks have soft bodies that are encased in hard shells. The shells of mollusks are made of calcium carbonate, which is a mineral that is also found in the shells of seashells. Mollusks use their shells to protect themselves from predators and from the elements.