Paasselkä devils (Finnish "Päässelän pirut") are stories about balls of light at lake Paasselkä, Finland. Local people say that bright balls sometimes move above lake Paasselkä or near the lake in the forest. This kinds of lights are said to appear around the world. They are sometimes called ghost lights or will o' the wisps. Scientists does not know what ghost lights or will o' wisps are. 