Researchers have found millions of "super" bacteria thriving inside the oxygen-starved Lake Diamante, in the center of a giant volcanic crater located over 15,400 feet above sea level.
The bacteria's habitat is similar to primitive earth, before living and breathing organisms began wrapping a protective atmosphere of oxygen around the planet.
The conditions -- which include high arsenic and alkaline levels -- could also shed light on life beyond Earth.
"This is of great scientific interest as a window to look to our past and also for a science called astrobiology, the study of life on other planets," said Maria Eugenia Farias, part of the team that discovered the life-forms in Lake Diamante earlier this year.
If bacteria can survive here, the theory goes, it could also survive somewhere like Mars.
So-called "extremophiles" have been found in other parts of the world -- and they can have significant commercial value. Bacteria that break down lipids are used in detergents for example.
But Farias said these bacteria, called "polyextremophiles" are exceptional because they flourish in the harshest of circumstances.
"What we have here is a series of extreme conditions all in one place. And this is what makes this place unique in the world," said Farias, a microbiologist at the National Scientific and Technical Research Council in Tucuman province.
The lake sports levels of arsenic 20,000 times higher than the level regarded as safe for drinking water and its temperature is often below freezing. But because the water is so salty -- five times saltier than sea water -- ice never forms.
The bacteria's DNA mutates to survive the ultra-violet radiation and low oxygen levels found at such high altitudes, which could make it of interest to the pharmaceuticals industry, Farias said. It could also have future commercial applications in products such as sunscreens, she added.
Farias and her team are looking for Argentine funding to produce a metagenome of the bacteria, an advanced study which provides a DNA sequence of the entire microbe colony.
This would enable her crew to study the bacteria in Argentina and help ensure that the South American country keeps hold of potentially lucrative patents for new antioxidants or enzymes that could be derived from the bacteria.
(Writing by Kristina Cooke; Editing by Cynthia Osterman)