Cartoon turtles have taught us that turtles retrieve into their shells when they don’t want to be seen, but that’s nothing but fiction. Anatomically, turtles don’t go inside their shells, because they are their shells. This means that, unlike what we’ve always believed, turtles don’t actually have a “shell,” rather, that’s the shape of their bodies.
As Twitter user Ada McVean reminds us, the turtle’s skeleton is shaped like a shell, which is meant to protect its vital organs. Turtles can retract their heads underneath their shells, but in contrast to what we were taught growing up, they don’t do so for protection. This means that, in contrast to what most people think, turtles cannot come out of their shells, since it grows with them.