These huge gypsum crystals in Mexico's Naica caves, some up to 12m long, have been growing for tens of thousands of years -- but scientists have only now discovered what's inside them. "We've recovered over 60 samples from tiny fluid pockets in the crystals," explains speleologist Penelope Boston, associate director of the National Cave and Karst Research Institute in New Mexico. "Nothing that we've found is known to science."
For the past four years, Boston has tried to identify the bacteria, viruses and archaea captured in the crystals against known records, but realised no one had ever seen them before. "The closest we can come to identifying them is to find their genetic relatives," says Boston. These relatives live as far afield as the volcanic soils of Russia's Kamchatka Peninsula and caves in Spain, Italy and Australia -- all places with similar environments to Naica, where temperatures reach 50°C with 100 per cent relative humidity.
The crystal caves, which were discovered in 2000 by Mexican mining company Peñoles, were opened to scientists in 2006, before being re-closed in 2010. When all the surrounding ores have been extracted, the water pumps will be switched off, and the caves will be re-flooded.