A bony case or covering on the back of an animal such as a turtle or crab.

The bottom half of a turtles shell. The plastron is made up of the turtles bones, which are fused (joined) together.

A strong, natural protein. Keratin is the main substance that forms hair, nails, horns, hoofs, and some animal shells (for example, the shell of the green turtle).

An animal (E.g. a shark, dolphin, or human) that naturally hunts and eats other animals.