Hans-Dieter Sues - Curator, Paleontology, National Museum of Natural History In a fit of pique, according to one of Aesop's fables, the god Hermes made the animal carry its house forever on its back.

It's a long-held idea that turtles can tuck their heads into their shells when threatened. But is it true? And is this protective trick why turtles the world over have shells today? The answer is that ...