Speleology

thumb|Grotte des Faux-Monnayeurs, Mouthiers-Haute-Pierre (France) thumb|Beam of sun inside the cavity of Rocca ill'Abissu, Fondachelli-Fantina|Fondachelli Fantina, [[Sicily]] thumb|Pirunkirkko (literally "devil's church") of Paistjärvi, a peak cave in [[Heinola, Päijät-Häme, Finland]]

thumb|right|A 3D cross-section of the Lukina jama–Trojama [[cave system in the Velebit mountains of Croatia. The collection sites (1) of the shells and the single living specimen (2) of the cave-dwelling snail Zospeum tholussum are indicated.]] thumb|The spider Trogloraptor marchingtoni from a cave in [[Oregon.]]