A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of
animal groups, including arthropods, such as crustaceans and arachnids, as
well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.
(definitely not copy pasted for google)
In cases of speech and sayings, it
may be used as a replacement for the word shell.