English: A fungus - Onygena equina The common name for this species, seen here as tiny mushrooms growing on a ram's horn, is "Horn Stalkball". This fungus isn't included in popular guides to mushroom identification; not only is it uncommon, but it also has a very unusual habitat: it is restricted to the remains of hooves and horns of certain animals. Sheep roam freely on the slopes where this horn was found; remains of horns are therefore not uncommon in the area. The fungus grows on keratin, which makes up horns (it also makes up human hair and fingernails).