Marill is a small, bipedal, blue mammalian Pokémon. It has a nearly spherical shape with a white underside, and round ears with red insides. Its arms and feet are short and possess no visible digits. It also possesses a zigzagging black tail with a blue "bubble" on the end of it. The tail's jagged appearance originally led people to believe that it was related to Pikachu. Marill's tail is flexible and configured to stretch.