from national geographic.com:

"A coil of teeth caps the lower jaw of a sculpture of a 13-foot (4-meter) whorl-tooth shark, or Helicoprion, a fish genus that lived about 250 million years ago.

Artist Gary Staab depicts the animal's jaw as something of a spiral conveyor belt, in which new teeth would advance to replace old ones (concealed here by skin) . But the true arrangement and purpose of the teeth remains a mystery. Some scientists suggest that it may have operated like a spiked whip, possibly curled underneath the lower jaw like a weaponized elephant trunk. "