Turtles have a shell because it provides them with protection!
Different types of turtles have different types of shells which all provide benefits in their own ways. Some turtles have special shells that allow them to bring their head, arms, and legs into their shell for complete protection from predators, while others (such as the Leatherback Sea Turtle) have softer, more leather-like shells that allow them to swim deeper down into the sea! Because a turtle’ shell is attached to its ribs and spine, a turtle can never “take **” or “leave” its shell.
