Mysterious Cave Houses World's Largest Crystals

"The cave here provides two bits of information with respect to the search of life," McKay said. "One is it tells us about life at high temperatures. That's interesting. But even more interesting, it tells us about how evidence of life is preserved over a long period of time, over geological time."

Despite their incredible sense of glory and amazement, the scientists realize the crystal cave will not live on indefinitely. Now that the crystals are exposed to less heat and no water, they are slowly but surely eroding away. In the meantime, however, the lessons that this crystal cave can provide are invaluable.

"By investigating the life in these environments, I think we expand our understanding of the limits to life," McKay said. "For us in planetary science, that understanding of the limits of life is the basis of our search. When you say, 'What are we going to look for?' Well, we're going to look for life."

"Giant Crystal Cave" premieres Sunday at 9 p.m. on the National Geographic Channel.