The Helicoprion is said to have lived during the Carboniferous period and was one of the few creatures able to live through the Permian-Triassic extinction event (‘The Great Dying’). Eventually the Helicoprion went extinct during the Triassic period. The creature had teeth that are very much like a circular saw. It had so many teeth because as new teeth grew, the older teeth were pushed out and into the middle to create the spiral. Length-wise the creature was said to be 10-15 feet.