Schizophyllum commune, commonly known as the split-gill mushroom, is a fungus that grows on wood and was historically considered just a common environmental organism. However, scientists discovered in 1950 that this mushroom could actually infect human tissue, causing conditions like nail infections. This discovery was surprising because mushrooms were not previously known to infect living animals. Today, researchers recognize it as an emerging fungal pathogen that can pose health risks to humans.