16. Helicoprion
The strange-looking Helicoprion is a pre-historic shark species that lived almost 300 million years ago. When fossils were discovered of the shark species, anthropologists and even marine biologists were flat-out amazed by it. The Helioprion has one of the craziest sets of teeth known among any animal species.
They had a spiral set of teeth, forcing many scientists to wonder how they fit them in their mouths. How their teeth seemed to work has been debated for years. What isn’t debated is that this shark likely terrorized the sea of its time, as it was quite large and its now-infamous teeth likely made it a prime predator.