In a Mexican cave system so beautiful and hot it is called both Fairyland and hell, scientists have discovered life trapped in crystals that could be 50,000 years old.
The bizarre and ancient microbes were found dormant in caves in Naica, Mexico, and were able to exist by living on minerals such as iron and manganese, said Penelope Boston, the head of NASA's Astrobiology Institute.
"It's super life," said Boston, who presented the discovery on Friday at the American Association for the Advancement of Science conference in Boston.
If confirmed, the find is yet another example of how microbes can survive in extremely punishing conditions on Earth.
Though it was presented at a science conference and was the result of nine years of work, the findings have not yet been published in a scientific journal and have not been peer reviewed.
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Boston planned more genetic tests for the microbes she revived in the lab and on site.
The life forms - 40 different strains of microbes and even some viruses - are so weird their nearest relatives are still 10 per cent different genetically.
That made their closest relative still far away, about as far away as humans were from mushrooms, Boston said.
The Naica caves - an abandoned lead and zinc mine - are 800m deep.
University of South Florida biologist Norine Noonan, who was not part of the study but was on a panel where Boston presented her work, said it made sense.
"Why are we surprised? As a biologist I would say life on Earth is extremely tough and extremely versatile," she said.
This is not the oldest extreme life: several years ago, scientists published studies about microbes that might be half a million years old and still alive.
Those were trapped in ice and salt, which was not quite the same as rock or crystal, Boston said.
