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 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