Witch’s butter is in old Swedish lore, the yellow vomit of witches’ cats found in gardens. In centuries past, it was believed that the Devil gave witches Cats, called carriers. The witches sent the cats out into the neighbourhood to steal food. The cats were wont to gorge themselves on the stolen food, which they then vomited in their neighbours’ yards. Witches’ butter also refers to a genus of the lowest group of freshwater algae, Nostoc, also called star spittle. After summer rain, Nostoc swells suddenly to a gelatinous mass, giving the appearance of having fallen from the sky.