Exoskeleton

The hardened parts of the external integument of an animal, including hair, feathers, nails, horns, scales, etc.,as well as the armor of armadillos and many reptiles, and the shells or hardened integument of numerous invertebrates; external skeleton; dermoskeleton.

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