Helicoprion
The Helicoprion is mostly known for its unique mouth. A cartilaginous structure helped the shark develop a strange tooth structure. Scientists believe that it lived during the Permian age approximately 290 million years ago.
The spirally-arranged cluster of teeth was known as “tooth whorls,” and the structures measure up to 18 inches in length. Experts believe these sharks were quite large and could grow up to 39 feet long. The fossils have been found in China, Australia, the Ural Mountains, and North America.