The fruiting bodies of the fungal genus Pilobolus are too small to be recognizable as mushrooms, but their reproductive spores do grow in a hat-like spore case or sporangium that rests on a globular structure supported by a slender stem. Pilobolus grows in dung. When mature, it forcefully shoots its spore case in the direction of optimal light, where it is likely to land on a blade of grass. If a horse or cow eats the grass with the spores attached and eventually eliminates the spores with its dung, Pilobolus germinates and repeats its life cycle.
The dung-dwelling Sordaria fimicola is an ascomycete, a fungus that develops spores in sac-like structures called asci. The cup-shaped fruiting body grows toward the light and also shoots its spores in the same direction. This mechanism expels the spores from the dung, where no ruminant would eat them, to an illuminated area, where grass is likely to grow. Like Pilobolus, the spores of Sordaria fimicola pass through the digestive system of a suitable animal and end up in its dung. The spores then germinate and repeat the Sordaria life cycle. Other ascomycete fungi that thrive in dung belong to the genera Podospora, Ascobolus, Chaetomium and Saccobolus.
Sphaerobolus is a basidiomycete fungus, the type that develops spores on rod-shaped structures. Its fruiting body looks like an egg in a bird's nest, so some classifications place it in the order Nidulariales with the so called bird's nest fungi. Sphaerobolus grows on such media as rotting logs and sawdust, but it also thrives on partially dried dung. Like other dung fungi, it disperses its spores by propulsion. Since the spore-filled missiles that it propels are sticky masses called peridioles, it occasionally disfigures cars or houses with sticky black spots. Other members of the order Nidulariales also thrive in dung. Cyathus stercoreus is an excellent example.
Fungi of the basidiomycete genus Coprinus thrive on dung. Coprinus comatus is an edible species. As the Coprinus fruiting body matures and spores are about to disperse, the mushroom that supports the spores turns black and disintegrates. This characteristic has given Coprinus species the nickname "inky cap."
Some dung-dwelling basidiomycete mushrooms possess hallucinogenic alkaloids. Because of the abuse to which these fungi have been subjected, various countries, and U.S. states have enacted legislation designed to control the possession and use of these plants. For example, the genera Psilocybe and Panaeolus have been objects of abuse and consequent legislation. The Aztecs attributed a divine virtue to such species as Psilocybe mexicana, and other Mexican Indian tribes have used these fungi in religious rites.