Subterranean wonders were known as far back as 1213, but the cavern remained undiscovered in modern times until 1816, and it is only in still more recent times that its vast extent has been fully ascertained and explored. The total length of the passages is now estimated at over 52 m. The connexion with the Ottokar grotto was established in 1890. The Magdalene grotto, about an hour's walk to the north, is celebrated for the extraordinary subterranean amphibian, the proteus anguinus, first discovered there. It is about a foot in length, lives on snails and worms and is provided with both lungs and gills.