Certain species of catfish are covered with bony plates bristling with thin teeth, similar to extinct vertebrate lineages. These teeth, which regularly fall out and grow back, are used for defense and, in males, to attract females. Researchers at the University of Geneva (UNIGE), Switzerland, wanted to understand how teeth capable of regeneration can develop outside of the mouth. They discovered that the extra-oral teeth only grow from bone, regardless of its type, even in the absence of a bony plate. This suggests a role for bone in the induction of dental tissue. These results, published in the journal Proceedings of the Royal Society B, elucidate the mechanisms of the formation and regeneration of teeth in all vertebrates, including in humans.