New Translucent Snail Species Discovered in Deepest Cave in Croatia

When you first see it, it looks like a swirling piece of spun glass. Light catches its curves, making it appear delicate and fragile. This piece of "glass" isn't glass, though. Instead, it's a shell--and part of a new species of a peculiar cave-dwelling snail in one of the 20 deepest cave systems of the world.

The newly discovered species is strange in appearance. Discovered in Lukina Jama-Trojama in Croatia, it possesses a beautifully-shaped, dome-like translucent shell. Yet only one living specimen of this creature was discovered during an expedition into the cave system. It was found at the extraordinary depth of 3,215 feet below the surface in an unnamed chamber filled with rocks, sand and a small stream.

In fact, the habitat where it lives is remarkable in and of itself. The Lukina Jama-Trojama is the deepest cave system in Croatia and is known for its vertical shape, long pits and great depth. From an ecological standpoint, this system is particularly interesting; it possesses three microclimatic layers with cold temperatures. The first, entrance part has a temperature of only about 1 degree Celsius. The second part has a temperature of up to 2 degrees and the third, bottom part can reach 4 degrees.

The new creature has been dubbed Zospeum tholussum and is known for its limited ability to move--like all cave-dwelling Zospeum species. Scientists believe that any dispersal of this species is through the passive transport via water or larger mammals.

"They only creep a few millimeters or centimeters a week, and mainly in circles, grazing at one point where they live," said Alexander Weigand, a taxonomist in Frankfurt, Germany, in an interview with NBC News.

The new species is a spectacular find. It shows that life can occur even in these extreme conditions deep beneath the Earth's surface.

The findings are published in the journal Subterranean Biology.