There are creatures on Erwt that defy the rules of common sense, and which generally don't follow the ordinary rules of physics. They come from the deep Ocean, where the difference between air and water, light and dark is indistinct. Most of them stay out there; their constitution doesn't stand up to the more rigid fabric of Erwt, and turn back when they encroach on the calmer waters near the coast. Some others are more resilient. The smallest of these are monsters and beasts.