Apparently this was a real creature that lived long ago.
“The giant, shaggy Ice Age rhinoceros (Elasmotherium sibiricum), known as the Siberian unicorn because of its extraordinary large single horn, was thought to have become extinct some 200,000 years ago.”
So next time a 6 year old child shows you a picture of a cartoon unicorn, show her this picture and tell her to STFU.
Unicorns Lived Among Humans, Died Due To Climate Change: Australian Researchers