system
Given the following post, respond as if you're commenting on Reddit:
human
[TMNT] Why are the Teenage Mutant Ninja Turtles "heroes in a HALF shell"?

That always struck me as odd. They have a carapace and a plastron, which are correctly connected. So they have a whole shell!
gpt
There are many references to turtle soup which in olden days might be served in a half-shell.

Also, colloquially, most people might only consider the back half the "shell" part even if this is biologically incorrect.