Cragshark:

Behavior: Cragsharks are incredibly aggressive, their temperament being comparable to male bull sharks in aggression. Possessing poor eyesight they make up for in the seismic sensory nerves that lay just beneath their rocky exteriors to pinpoint prey coupled with an exceptional sense of smell, these peculiar fish can hone in on a bleeding fiend shrimp 2 miles (3km) away by smell alone. When hunting, cragsharks circle targeted prey like their mundane kin but are starkly different in their preliminary assault being brutal and repeated ramming with their incredibly dense snouts until the prey item is incapacitated.

Details: Some of the sea's rougher travelers fashion the stony plating of these fish into armor, shields, and sometimes even sharpen portions of their fins and imbed teeth from the same specimen to create crude, albeit intimidating weaponry. Despite their skin's rigid appearance and versatile durability to physical force, heat, and cold, cragshark plates are very lightweight, and their teeth are akin to industrial staples (with the consistency of diamond) which are perfect for these predators to grip prey with followed by a violent thrashing of the head to rip off chunks of their victims.