Shark fossils show that weird sharks are not just a modern development. Although we know little about it, the whorl shark (Helicoprion) is a truly strange fish that lived 280-225 million years ago. The whorl shark's distinction is a spiral of teeth it left behind. Modern sharks continue to grow teeth throughout their lives and shed old teeth. Ancient sharks grew new teeth, but kept the old teeth as well. In some species, old teeth migrated to the face to make room for teeth in the jaw. In the whorl shark, old teeth were just rotated around. But where inthe shark were these teeth? Full fossils have not yet been found.