European Tortoise Retreating into Shell
Despite what your childhood cartoons told you, turtles and tortoises can’t actually “take off” their shells…the shells are an integral part of their body and grow with the reptile, unlike, say, hermit crabs. There’s no skin underneath the shell, since the shell IS the outermost layer. Long story short, don’t try to literally take a tortoise out of its shell; you’ll kill it, and that’s not cool.
The Principal Forms of the Skeleton and of the Teeth. Dr. Richard Owen, 1854.