The fish kick, a very difficult technique in swimming where the swimmer turns sideways and mimics the motion of an eel, is arguably the fastest way to swim and was used in the 2000 Olympics by Misty Hyman to win the 200m butterfly.–WTF Fun Facts
Source: https://coachsci.sdsu.edu/swim/champion/hyman150.htm
An ancient shark fossil that looks a lot like an eel was found in Morocco. The fossil belongs to the ancient shark genus Phoebodus which lived 360 million years ago. – WTF Fun Facts
Source: https://www.nationalgeographic.com/science/2019/10/amazing-fossil-shark-skeleton-first-of-its-kind-phoebodus-morocco/