It's a rhinoceros horn. Given that rhinos are one of the the creatures which may have inspired the unicorn myth, that horn is absolutely right.
As far as "most dangerous animals" -- Dunno why, given that there are lots of other horned critters out there, some of whom have an equal reputation for nasty tempers. Consider the fact that Yellowstone Park, which has finally convinced city-slicker tourists that Bears Aren't Cuddly, is now having to advise them that bison are also dangerous. (A ton of muscle, two horns, can wreck a bus if they're feeling threatened. "They can run 35MPH. You can't." Herbivorous does not mean harmless.)