Rhino horn

[Iceman-999]

How can a Rhino horn be hardwhen it is made of hair

[B00]

It's compacted hair

[smudge2279]

The next time you get a hair-cut, pick up a few hairs and twist them together. Add some more and keep twisting. Eventually, you will have an object in your hand which is harder than a strand of hair. As a rhino's horn grows, the strands of hair that make it up intertwine together for a long period of time. The end result is a very hard horn which, although very dangerous, can actually be pulled apart to demonstrate it's components, i.e hair.

[wildwood]

Pretty much like porcupine quills, also modified hairs.

[cliveminni]

maybe they use hair gel! ;)