It's the biggest solid piece of shell in English. Like the stuff over a crabs pincers is still shell but only the stuff that surrounds the main body is the car

It's the biggest solid piece of shell in English. Like the stuff over a crabs pincers is still shell but only the stuff that surrounds the main body is the carapace. Often used as an analogy for other sorts of armor, like a knights breastplate being his carapace or a tank's hull armor.