Underneath our feet, water lurks along murky tunnels. No light penetrates the never ending darkness. The substratum is muddy and dank. Weird, limiculous creatures reside within this rather univiting habitat- including the subterranean sponges of Italy.

Unlike cave men, cave sponges are quite adapted to their environment. Subterranean cave sponges lack photosynthetic and light interactions. Energy levels are reduced considerably.

 Demospongiae is the only class including subterranean and freshwater sponges. Generally, freshwater sponges are very closely related to their marine relatives. Also, they are not completely dwellers of freshwater. In correlation to the waters, it is often brackish, containing at least some fraction of salt. Within the caves, the sponges live partially in light and in the proximity of the cave entrance. These are not entirely freshwater. Classifications living entirely in freshwater are stygobitic- a very rare group.

Recently, in Italy and surrounding areas of the Mediterranean, stygobitic sponges have been discovered! In Italy, there are at least twenty-five species of the rare stygobitic group. The caves inhabited by these sponges are completely freshwater. Such species live entirely in darkness, but they probably don't notice the difference as much as a human would, being accustomed to darkness.