Dry rot species of fungi cause brown rot decay, preferentially removing cellulose and hemicellulose from the timber leaving a brittle matrix of modified lignin. The term "dry rot" is somewhat misleading, as both species of fungi "Serpula lacrymans" and "Meruliporia incrassata" require an elevated moisture content to initiate an attack on timber (28–30%). Once established, the fungi can remain active in timber with a moisture content of more than 20%. At relative humidities below 86 percent, growth of "Serpula lacrymans" is inhibited, but it can stay dormant at relative humidities down to 76 percent. These relative humidities correspond to equilibrium moisture contents
Serpula vermicularis divided into two. The yellow-coloured body has seven thoracic segments and up to 190 abdominal segments which are protected by the tube. At least four segments with setae (bristles) are found in the thoracic region. "Serpula vermicularis" is cosmopolitan in distribution. It is found in the Pacific and Indian Oceans and the European seaboard of the Atlantic Ocean, but not on the North American coast. It occurs in the intertidal zone and at depths down to . Also along Southern African coast from Olifant's River to Maputo. "Serpula vermicularis" grows on hard substrates. It favours shells of bivalves, boulders and