Why are shells a good home? They are great home for lots of animals. Like sea snail,crabs,snail,,limpet,paua,mussel,scallop,clam,oyster,chiton.SHELLS ARE AWESOME!!!!!!!!!!!Shells protects them from predators.You can find shells anywhere you go like the sea,beach, grass,rocks,road,algae.Most seashells come from mollusks, a large group of marine animals including clams, mussels, and oysters, which exude shells as a protective covering. Shells are excreted from the outer surface of the animal called the mantle and are made up of mostly carbon dioxide.