Marco Polo thought rhinoceroses were unicorns

One of the fun facts about Marco Polo, he thought rhinoceroses were unicorns.

Marco Polo announced to the world that he had discovered unicorns during his travels through the islands of Sumatra in the 13th century. There were "numerous unicorns," he wrote, "very nearly as big" as the "wild elephants" he had also discovered in the same habitat. He had not only found one. They were not the majestic horses he had anticipated; instead, they were said to be so pure that, according to legend, they would only lay their heads on the lap of a virgin maiden. They did, in fact, resemble a species that one might anticipate to find on the island he called Java the Less: the rhinoceros. Polo told his readers that unicorns mostly enjoyed rolling around in the mud and dirt and biting people with their sharp tongues. Historians now understand that Polo was actually describing the rhinoceros when he described the "unicorn" in his writing.

However, Marco Polo was unaware of rhinoceroses. He knew unicorns existed, so any animal that moved on four legs and had a horn on its nose had to be a unicorn, even if it was a rather unimpressive example of the species. The Asian two-horned rhino was the rhinoceros he was most likely to encounter in Sumatra, so the fact that the rhinos he came across most likely had two rather than one horn on their noses did not sway his opinion. It had to be a unicorn if it had four legs and a horn on its nose.