Meet pentecopterus, a giant sea scorpion; Predator from prehistoric seas

You don't name a sea creature after an ancient Greek warship unless it's built like a predator. That's certainly true of Pentecopterus, a giant sea scorpion with the features of a penteconter, one of the first Greek galley ships. Researchers say Pentecopterus lived 467 million years ago and could grow to nearly six feet. It is the oldest described eurypterid -- a group of aquatic arthropods that are ancestors of modern spiders and ticks.