The pufferfish is a very curious animal for lots of reasons; it swallows air or water to make itself larger and more threatening, it combines its combining pectoral, dorsal, anal, and caudal fins into one set of fins (like a seahorse), and it is often super poisonous. But Dr. Gareth Fraser of Sheffield University is focused on the puffer for a different reason: its teeth.
The puffer, like lots of bony fish (meaning, not cartilaginous), constantly regrows its teeth. The puffer doesn't have delineated teeth like most other fish, though; instead, after its first set of teeth have fallen out (like human baby teeth), it grows a solid structure that looks like a beak. This beak is made of horizontally growing layers of dentite, the usual tooth material for fish, but appears as a single band.
Fraser managed to map the specific cells responsible for the constant regrowing of teeth in the puffer