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 vigorous pumping movements of the abdomen and also by the activity of the ciliary tracts. The well-developed longitudinal muscles of the body wall of serpulids lack a special blood supply. The body surface in the larger serpulids, like "Serpula", has a rich blood supply, and the water in contact with this surface is constantly renewed. It seems probable that the outer body surface of serpulids serves as a respiratory membrane, supplying oxygen to the underlying muscles by diffusion. The biochemistry of the blood of "Serpula" is especially unusual in that the blood contains not only hemoglobin, but also chlorocruorin. While