Subterranean biology (biospeleology or speleobiology) is a biological discipline that studies biology of organisms living in subterranean habitats. These are mainly caves, but also other subterranean habitats in different geological substrata (interstitial habitats, MSS, hypoterlminorheic, calcretes, springs,…). Organisms include all life underground, from bacterial communities to numerous invertebrate and vertebrate species occurring in or living exclusively underground.