Narwhals are often called the “unicorns of the sea” thanks to the long, spiral tusk that juts from their heads. This tusk, which is actually an elongated tooth, can grow up to 10 feet long and ...

This weird-looking animal is not one to mess with either — they use their bills to decapitate their prey, and their food sources consist of large fish, water snakes, eels, and even small crocodiles.

It pushes off from all four feet and hops straight up in the air, looking like a kernel of popcorn in a microwave. Guinea pigs aren't the only animals that popcorn, as this behavior is called.

Here are just a few groups of ancient animals that live on: And, here are the animals that get my vote for “most prehistoric-looking.” They may not be the oldest animals on Earth, but they ...