carapace

(kărˈə-pāsˌ)

1. Zoology A hard bony or chitinous outer covering, such as the fused dorsal plates of a turtle or the portion of the exoskeleton covering the head and thorax of a crustacean.
2. A protective, shell-like covering likened to that of a turtle or crustacean: “He used to worry that Sarah would age the same way, develop the same brittle carapace” (Anne Tyler).