Exoskeleton
WordNet
noun
(1) The exterior protective or supporting structure or shell of many animals (especially invertebrates) including bony or horny parts such as nails or scales or hoofs
WiktionaryText
Etymology
From εξωσκελετός (exoskeletos), from Ancient Greek έξω (exo) "out, outside, without, but, except" + σκελετός "skeleton".