Sea scorpions, also known as eurypterids, were a group of ancient aquatic arthropods that lived from the Ordovician Period to the Permian Period, approximately 470 to 252 million years ago. They were not true scorpions but had some superficial similarities to them, including a long, segmented body and a pair of large pincers called chelicerae.
Sea scorpions were among the largest arthropods that ever lived, with some species reaching lengths of over 2 meters (6.5 feet). They inhabited both marine and freshwater environments, including shallow coastal waters and estuaries. Fossil evidence suggests that they were active predators, feeding on a variety of prey such as smaller arthropods and fish.
These creatures had a carapace-like exoskeleton, compound eyes, and multiple pairs of appendages. The last pair of appendages, known as swimming or paddling legs, were modified for locomotion in water. The anterior appendages, or chelicerae, functioned as grasping or cutting appendages.