Chitin n. (Chem.) A white amorphous horny substance forming the harder part of the outer integument of insects, crustacea, and various other invertebrates; entomolin.
... press his advantage and landed a beaut on the Nipe's lower left eye. Then he tried a body blow. It wasn't too successful. The alien had an endoskeleton, but he also had a hide that was like somewhat leathery chitin. ... — Anything You Can Do ... • Gordon Randall Garrett
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