Scientists have discovered what they believe to be the first large predatory animal--and it's the stuff nightmares.

Evidence of the prehistoric sea scorpion was found in Iowa in the form of over 150 fossils found deep beneath the Upper Iowa River, according to the Associated Press. Scientists at Yale later determined that the fossilized creature was a new species from more than 460 million years ago when Iowa was submerged underwater.

The new species of sea scorpion found is believed to have been as large as a human, growing nearly six feet in length, according to CNN. It had a long head, slim and narrow body, and large claw-like limbs used to hunt and fight.

Scientists have named the creature the Pentecopterus decorahensis after a Greek warship, according to ABC News.

It's part of the eurypterid family, an ancient group that is shared with modern species like spiders, lobsters and ticks, according to CNN.

"Perhaps most surprising is the fantastic way it is preserved -- the exoskeleton is compressed on the rock but can be peeled off and studied under a microscope," James Lamsdell, the lead author of the study at Yale University, said in a statement.

"This shows an amazing amount of detail, such as the patterns of small hairs on the legs. At times it seems like you are studying the shed skin of a modern animal - an incredibly exciting opportunity for any paleontologist," he said, according to ABC News.