PHDID YOU KNOW? 
A rhinoceros' horn is made of hair.
The horn of the rhinoceros is not a horn in the traditional sense like the horn of a cow or the nail of a hoof, though it does share some material properties. The rhino’s horn is actually a tuft of hair that grows, tightly packed and glued together by exudates from sebaceous glands, on the nose of the animal.
In this proof of concept, the scientists bundled together tail hairs of the rhino’s near relative, the horse, and glued them together with a bespoke matrix of regenerated silk to mimic the collagenous component of the real horn. This approach allowed them to fabricate sample structures that were confusingly similar to real rhino horn in look, feel and properties. Analytical studies demonstrated similarities in composition and properties with natural and the faux horns.
(s)OxUK