Have you ever eaten a mushroom pizza? If so, you’ve tasted a fungus—a strange, spongy life-form that’s neither an animal nor a plant. Mushrooms, mold, and yeast are some of the most well-known types of fungi. But there are millions of species, from single microscopic cells to tangled masses as big as whole towns!
Though they can sometimes look like plants, fungi are more closely related to animals, explains Sydney Glassman, an ecologist who studies fungi at the University of California, Riverside. Many have a dirty but important job for the environment. When plants and animals die, fungi move in to break them down and recycle their nutrients. “If fungi didn’t exist, you’d be up to your ears in dead stuff,” says Glassman.