Sharks have no overlapping scales covering their bodies like other fish. Instead they have a very rough skin that feels like its covered with very small teeth. Dried shark skin was once used as sandpaper.
Sharks keep growing their teeth throughout their lives.
When one wears out or breaks off a new one moves up to replace it. Sharks are predators. Filter feeding sharks strain small fish, krill and plankton. Any and all copyright material is acknowledged as of their respective owners.