The olm, or proteus (Proteus anguinus), is a blind amphibian endemic to the subterranean waters of caves of the Dinaric karst of southern Europe. It lives in the waters that flow underground through this extensive limestone region including waters of the Soča river basin near Trieste in Italy, through to southern Slovenia, southwestern Croatia, and Herzegovina. The olm is the only species in its genus Proteus, the only European species of the family Proteidae, and the only European exclusively cave-dwelling chordate. The other six species live in the east part of USA, mostly in surface waters.
European / Slovenian species:
and one of the six species that inhabit USA: