Shell Facts

A shell is a hard outer layer, which has evolved in a very wide variety of different animals, including molluscs, sea urchins, crustaceans, turtles and tortoises, and armadillos. See the fact file below for more information about shells.

  • Common types of shells include sea shells, snail shells, turtle shells and eggshells.
  • 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.
  • 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.
  • Seashells are primarily made of calcium.
  • Shells protect the creatures from predators, strong currents and storms.
  • Shells also help camouflage some animals.
  • 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.
  • 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.
  • Ancient peoples cleaned out and removed the living organisms from the shells, and used them as containers for food and water.
  • Hermit crabs use discarded mollusk shells for self-protection. As the hermit crab grows, it will look for larger shells to use for protection.

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