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 Vertical ciliary tracts in the grooves between adjacent abdominal segments move particles toward the abdominal fecal groove. Once in the abdominal fecal groove, further ciliary currents transport particulate matter (feces, gametes, etc.) from the depths of the tube, through the thoracic segment to the aperture where it can be released to the sea. Worms of the genus "Serpula" have a very unusual dual circulatory system, consisting of a central system of large vessels through which a continuous true circulation of blood is maintained, and also a peripheral system of small, predominantly blind-ending vessels which alternately empty and fill in a