Remote Lechuguilla Cave, which lies 1,600 feet (488 meters) below New Mexico's Carlsbad Caverns, is the deepest limestone cave in the U.S. The cave's more than 136 miles (220 kilometers) of underground passages form one of the planet's most sprawling subterranean networks.
But it's not just the cave's size or its breathtaking 20-foot (6-meter)- tall gypsum chandeliers and other exotic rock formations that fascinate scientific researchers. The cave is also home to an assortment of rock-eating bacteria that feed on the sulfur, iron and manganese deposits found inside [source: National Parks Service].
Scientists have been collecting samples of these microorganisms in an effort to find new potential antibiotics. One promising example is a microscopic predator that goes after other bacteria. Scientists hope that one of these microorganisms may extend the life of Cubicin, currently a drug of last resort against MSRA [source: Tirrell].