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 ...

In lab tests, snails raised in water with green crabs nearby—signaled to the snails through "risk cues" like smell and ...

‘I’m always amazed that people hate slugs so much. I don’t know what a shell does to a snail to make it lovable,’ says Jon. Slugs actually do have a shell, but it’s internal. Their shell has been ...