Helicoprion is a prehistoric cartilaginous fish that first appeared in the Carboniferous ocean finally extinguished in the Late Triassic, about 225 million years.
Helicoprion is thought may have reached a size of about 7 meters long and about 2 tons.
Since you do not have any skull, his way of feeding or predation techniques fall within the realm of speculation. One hypothesis is that fed on ammonites and their teeth were specialized in the task of breaking the shells of these animals.
Have been found in many parts of the world, which indicates its success in a given period.
Here I leave some pictures of different artists and their fossils.