Serpula lacrimans (formerly called Merulius) is one of the basidiomycetes which causes brown rot of wood (dry rot). This fungus is most closely related to Poria and other wood rotting polypores. These fungi can digest the cellulose components of wood. A small amount of decay markedly alters the strength of the wood. If the macroscopic fungus fruiting body is collected, it may be identified as a polypore (bracket fungus). The polypores belong to a limited group of fungi capable of attacking wood and using it for food. Wood with brown rot can be identified by observation of typical squarish cracking transverse to the grain of the wood. The wood also shrinks and becomes some shade of brown. The other general type of wood decay is called white rot, where all components (cellulose and lignin) are removed in differing proportions at different rates, and the decayed wood is light-colored. The strength factor is more slowly altered, and frequently the decayed wood is still usable in the early stages of decay. The natural habitat of the polypores is wood, i.e., slash in forests. No information is available regarding health effects, or toxicity. Allergenicity has not been studied.