An organism discovered deep in the ground has taken astrobiologists by surprise. The organism’s unique ability to live in complete isolation from other species, or even light or oxygen, suggests it could be the key to life on other planets. It was discovered in fluid-filled cracks in a South African gold mine, nearly three kilometres beneath the Earth’s surface. When US scientists analyzed the fluid, they expected to find genes from a mix of species. Instead, they found that 99.9 per cent of the DNA belonged to just one bacterium, a previously unknown species. Such a self-sufficient organism is virtually unheard of. It means that this organism extracts everything it needs from an otherwise dead environment. Almost all other known organisms on the Earth that do not use sunlight directly do use some product of photosynthesis. However, this newly-found organism gets its energy from the radioactive decay of uranium in the surrounding rocks. It also has genes to extract carbon and nitrogen from its environment, both of which are essential for making proteins. Scientists believe that this organism is just the type that could survive on a planet other than the Earth.