From Old English 'sciell' (husk), from PIE *skel- (to cut, split) — a shell is something you break apart.
The hard outer covering of an animal, egg, or nut; an explosive projectile.
From Old English 'sciell' meaning 'shell, husk, eggshell,' from Proto-Germanic *skaljō (scale, shell), from PIE *skel- (to cut, split). A shell is something that splits off — a husk you break apart. Key roots: *skel- (PIE: "to cut, split").