Sharks may scare most people but even they'd have been swimming away in fear from this gruesome-looking fish.
It's called the Dunkleosteus and experts reckon it had one of the most powerful bites of any animal ever.
They think the 10-metre (33 feet) long marine monster was powerful enough to bite a shark in two when it was feeling peckish and fancied a snack.
It lived around 400 million years ago and was munching on other animals long before dinosaurs appeared.
Scientists in the US used a fossil of the Dunkleosteus' skull and made a model of it in a computer with muscles to show how big its bite was.
They worked out it used two bony blades to snap and crush almost anything living in the seas with it.
One of the scientists behind the research said: "A huge great white shark is probably only capable of biting at about half that bite force."
The Dunkleosteus was covered in armour too and probably picked on sharks, as the first sharks were around millions of years ago as well.