Stethacanthus is a Carboniferous and Devonian Shark that lived in the fresh water swamps and oceans of the time. It ate mostly amphibians, smaller fish, other sharks and reptiles that make its way into its territory.  During the Devonian, it is preyed on by much larger fish such as Dunkleosteus but he became the predator at the top of the food chain in the Carboniferous period.. Like all sharks it had good sense to pick up blood or prey falling into the water. Unlike many shark fossils it comes nearly complete with a image of its odd decorator fin.