Exoskeleton

                                                    20. Exoskeleton

This is a picture of a crab. Crabs have an exoskeleton which is a skeleton on the outside of the body. For example, when the crab dies it often will leave behind its exoskeleton. That's why on the beach one might find what they think is a crab but it will actually just be a the exoskeleton of a dead crab.