These extinct animals belong to a group of aquatic arthropods during the Middle Ordovician period, which existed roughly 467.3 million years ago. These giant sea scorpions were predators of the prehistoric seas. It’s a genus of eurypterid, and contains only one species that surpasses the other eurypterids by 9 million years. Modern day sea scorpions aren’t dangerous, but can still cause a minor injury if you accidentally come into contact with one. If we existed millions of years ago and accidentally stumbled upon a giant sea scorpion, it might be a different story (Wikipedia).