Marill is a small, blue, bipedal semi-aquatic rodent Pokémon. It has a nearly spherical shape with a white belly, and has round ears with red insides. These sensitive ears can detect distant sounds. Marill's arms and feet are short and possess no visible digits. There is a blue, bubble-like ball at the tip of its zigzagging black tail. The tail is flexible and configured to stretch, and the ball is full of oil that acts as a buoy to help keep Marill afloat. The ball at the tip of its tail can glow when Marill attacks. In the anime, Marill was shown to be able to bounce on its tail. (Source: Bulbagarden.net, CC BY-NC-SA)