If you have ever collected shells at the seashore, probably most of the shells you found were once the homes of living animal called mollusks.
The most familiar mollusks are probably clams, oysters, octopuses, squids, snails and slugs.
Most mollusks are related, or alike, in certain ways. Mollusks are soft-bodied animals without bones.
Most kinds of mollusks, including clams and oysters, have hard shells that protect their soft bodies.
Other kinds, such as cuttlefish and squids, have no shells that show. A special shell grows inside their bodies.
Octopuses and some slugs have no shell at all.
Mollusks live in most parts of the world. Some, such as snails and slugs, live on land. Others are found in rivers, lakes and ponds. But the greatest number of mollusks are ocean dwellers.
Mollusks furnish us with food. Their shells are made into many products, including buttons and jewelry. – Dick Rogers