1. Common types of shells include sea shells, snail shells, turtle shells and eggshells.
2. There are more than 50,000 varieties of mollusk shells. Some open like clam shells, while others are shaped in a spiral and have a single hold where the animals enters and exits the shell.
3. Seashells are the external skeletons of a class of marine animals called Mollusks. People and mammals have their skeletons on inside of their bodies, but mollusks have their skeletons on the outside.
4. Seashells are primarily made of calcium.
5. Shells protect the creatures from predators, strong currents and storms.
6. Shells also help camouflage some animals.
7. Some seashells have holes in them. The holes were made by predators who drilled or chipped their way through the shell to get at the animal inside.
8. Shells are big business. Shells are sold in tourist attractions near oceans. Jewelry and adornments for clothing or household items are sold all over the world.
9. Ancient peoples cleaned out and removed the living organisms from the shells, and used them as containers for food and water.
10. Hermit crabs use discarded mollusk shells for self-protection. As the hermit crab grows, it will look for larger shells to use for protection.