Skin microflora can be commensals, mutualistic or pathogens. The human gastrointestinal tract is colonized by a vast community of symbionts and commensals. Secondly, helminths, non-pathogenic ambient pseudocommensal bacteria or certain gut commensals and probiotics, drive immunoregulation. "Labyrinthula" have been found to live as pathogens, commensals or mutualists on several host organisms. However, opportunistic pathogens are commensals by nature. The organisms are commensals of mucosal surfaces and sometimes give rise to opportunistic infection. Surprisingly, the adult flukes are regarded as commensals and non-pathogenic. Although previously considered harmless commensals, authors have since reclassified them as parasites. Two prominent murine human commensals have become vital laboratory animals. Entamoeba is a genus of Amoebozoa found as internal parasites or commensals of animals. This behaviour could be an attempt to dislodge parasites or commensals. The organisms listed below have been identified as commensals in the healthy uterus. Others are harmless commensals of mammals and humans or occur in water or soil. A number of crustaceans have evolved as commensals with Limnoriidae. Most burrow or build tubes in the sediment, and some live as commensals.