A hippocamp, or hippocampus (you might have seen a few when learning about greek mythology) is part fish, part horse. I know as a kid I thought the name was stupid, and I still think it sounds stupid -  but – its what they are called most commonly. I prefer the term waterhorse, but there was a movie made about a lochness-monster-like-cute-thing they called a waterhorse, so in a way that’s been taken.  We also all know what a sea horse is – so – for now its a hippocamp off record as well.