Schizophyllum commune is a macrofungus, commonly called the "Split-Gill." It looks like a polypore but has uniquely splitting gills, and has been placed in its own family, the Schizophylaceae, by most taxonomists. It has been found growing on a variety of domestic materials, including plaster. These small bracket-like fungi are whitish, hairy, with tough leathery flesh. They may remain dry for 50 years and when moistened will unroll their gills and begin shedding spores. Adverse health effects are rare but cases of the following in have been reported: brain abscess (1996), fungus ball in the lungs (1995), sinusitis (1992, 1990, 1986, 1956), allergic bronchopulmonary mycosis (1994), ulcerative lesions of the hard palate (1973), chronic lung disease (1956), meningitis (1955), and onychomycosis (1950). No information is available regarding toxicity and allergenicity has not been well studied. Identification is made when the macro fungal bodies are collected and submitted. The basidiospores are somewhat distinctive and would be identifiable on spore trap samples if large fruitings are present within a building. In addition, this is one of the few macrofungi that grow and fruit on general fungal media. Our laboratory has isolated this fungus on Andersen samples from buildings with large numbers growing on wooden building materials. Natural outdoor habitat of this fungus is hardwood sticks, stumps, and logs, with a worldwide distribution. Photographs of this fungus are available in the book Mushrooms Demystified by David Arora, available at most local bookstores.