Question: how does its "regeneration" work?

Lesser-Spotted Catshark answered on 7 Nov 2017:

Tooth regeneration works by keeping a group of undifferentiated stem cells at the back of the ‘conveyor-belt’ of teeth. Periodically, these stem cells divide and start forming new teeth, pushing the rest of the row forward and eventually right out of their mouths! We don’t know how these stem cells know when to divide, where to go, or what shape to take. But by sequencing the genome we can find this out and help answer your question!