Grimer is a purple pile of semi-hardened, poisonous sludge. It has saucer-like eyes and a gray mouth. Grimer may be distantly related to Koffing (since both Pokémon are associated with pollution, and whose evolutionary lines are the only ones to learn Sludge). Grimer emits an odor so strong and disgusting, many cities in the Pokémon world have been evacuated because of its presence. Since Grimer's body lacks a solid form, it can slip through the smallest of openings. Grimer thrive anywhere there is pollution and even feed on it. As it moves, it loses bits of its body from which new Grimer emerge, which worsens the stench around it. Grimer also exudes a germ-infested liquid from its body that acts as a herbicide and makes the land around it uninhabitable for any new plants. Not even weeds will grow in the path of a Grimer. There is some dispute over how a Grimer came to be. Some Pokédex entries claim that a Grimer was born when sludge in a dirty stream was exposed to the moon's X-rays. The Pokédex in Pokémon Sapphire states that a Grimer was born from the sludge that settled on a polluted seabed.