What is a seashell?
It's the skeleton of a mollusc, a kind of sea animal that doesn't have a skeleton inside its body. The shell forms a protective layer around the animal – it's called an exoskeleton; “exo”means outside.
There are two types of molluscs. Gastropods look like slugs and have a “foot” on the bottom of their body which they use to move around. Their shells consist of one piece. Then we get bivalves, like mussels – their shells are made