Wood-decay fungus fungi of certain types remove cellulose compounds from wood and hence the wood becomes brown colour. Brown rot in a dry, crumbly condition is sometimes incorrectly referred to as "dry rot" in general. The term "brown rot" replaced the general use of the term "dry rot", as wood must be damp to decay, although it may become dry later. Dry rot is a generic name for certain species of brown-rot fungi. Brown-rot fungi of particular economic importance include "Serpula lacrymans" (true dry rot), "Fibroporia vaillantii" (mine fungus), and "Coniophora puteana" (cellar fungus), which may attack timber in buildings. Other brown-rot
Serpula just behind the head. There is a median, longitudinal, ciliated, thoracic fecal groove on the dorsal midline of the thorax. It is a broad, shallow, relatively indistinct trough running the length of the thorax and ending at the head. Worms of the genus "Serpula" have a distinct abdominal region, composed of up to 190 very short, wide segments. The terminal body region is the tiny pygidium, on which the anus is located. A fecal groove extends the length of the ventral midline of the abdomen. The fecal groove spirals across to the dorsal position as it reaches the thoracic region.