The narwhal has a single horn (actually a giant protruding tooth) and if unicorns existed in the sea, went the argument in medieval times, surely they also existed on land.

• 海中的独角兽--独角鲸只拥有一只角（实际上是一个巨型的突牙），因此中世纪有观点表示：既然有独角兽生活在海中，那么它同样会生活在陆地上。