Carapace

In the anatomy of turtles (including s and s), the carapace is the larger, rounder part of a turtle shell. In an ordinary turtle, the carapace is the top part of the shell. In a humanoid mutant turtle, the carapace comprises the turtle's back behind the neck. Both the carapace on top and the plastron on bottom are part of a turtle's shell, but because of its overwhelming visual prominence, the carapace is sometimes mistaken for being the turtle's entire shell, for example in Chuck Lorre's 1987 TV series theme song whose lyrics refer to the carapace as a half-shell.