Serpula (fungus) are formed. The strand mycelium of "Serpula", which can be up to 8 mm thick, are invasive and can spread over non-nutritive surfaces to find new food sources, even spreading through pores in stone, brickwork, and cement. After its initial growth period, the fungus can produce the water it needs and can continue growth into dry timber, eventually degrading it to powder—hence the term "dry rot". "S. lacrymans" is the most serious cause of building timber decay in the UK and northern Europe. The "Dictionary of the Fungi" (10th edition, 2008), suggests that the genus contains two species. , the
Serpula lacrymans needed to promote "Serpula lacrymans" growth. In terms of aeration "Serpula lacrymans" often grows near ventilation shafts which shows a preference for concentrated oxygen. A moisture content of 30 to 40 percent is its ideal level in wood to promote fruit body formation. It appears that "Serpula lacrymans" requires an environment where both inorganic and organic materials are present. The fungus uses calcium and iron ions extracted from plaster, brick, and stone to aid the breakdown of wood, which results in brown rot. Although it is a common indoor biodeterioration agent, it has only been found in a few natural