It harbours a unicellular "Trebouxia" green algal symbiont. They may resemble a mutualistic symbiont or a species of little relevance to the prey. The vacuole structure containing the symbiont is therefore termed the symbiosome. One exception is the "Buchnera", an obligate maternally transmitted symbiont of aphids. Complex interdependence occurs between host and symbiont. EcM fungal partners characteristically suppress root hair development of their plant symbiont. "Heterorhabditis" nematodes are hosts for the "Photorhabdus" bacterial symbiont. While other species like that of the UNCY-A symbiont and Richelia have reduced genomes. Analysis showed that "R. pachyptila" symbiont has at least one gene needed for flagellum synthesis. Lela Dax is the first host of the Dax symbiont. The layer beneath the symbiont layer called is called the "medulla". The majority of the genes from the symbiont have been transferred to the nucleus. Borg symbiont in order to evolve itself into a 10th generation Borg symbiont. Audrid Dax is the fourth host of the Dax symbiont. Emony Dax is the third host of the Dax symbiont.