Mushroom Gills 

Although we call mushrooms “plants,” strictly speaking they aren’t, because they don’t contain chlorophyll and don’t make their own food. Instead, they belong to the group of organisms known as fungi (fungus, singular), which also includes less pleasant species such as mildew and athlete’s foot. The actual body of a mushroom is invisible, consisting of a network of tiny filaments growing underground, while the structures we see and sometimes eat are only what the mushroom uses to make baby mushrooms, i.e. reproductive organs. These reproductive bodies produce spores along the numerous thin membranes, or “gills,” seen in this worm’s-eye view of a mushroom.