Garnet crystals found in Thailand have yielded the first-ever evidence of life nestled within their hard material, reports Motherboard.
The gemstones first came into focus after it was discovered that they were traversed by a series of tiny tunnels, which spoiled their jewelry-like quality.
These labyrinths are now believed to be the work of burrowing microorganisms, which either found cracks in the garnets and let themselves in, or drilled intricate tunnels themselves and cozied up into their precious (literally) homes.
According to Phys.org, boring microbes like to make a home in all sorts of hard materials. Called endolithic organisms, these creatures have been known to tunnel into rock, wood, shell, and even bone.
Yet this is the first time that endoliths are suspected to have inhabited garnets — very hard gemstones that can only be penetrated by diamond or sapphire grains, notes the New York Post.
This unusual find is detailed in a study led by geobiologist Magnus Ivarsson of the Swedish Museum of Natural History and published today in the journal PLOS One.
Intrigued by the strange cavities uncovered in the garnets, which came from river sediments and soils, Ivarsson set out to unravel what could be causing them. After studying the gems with sensitive microscopes and spectrometers, his team established that the tiny shafts were excavated by burrowing microbes — at least to some extent.
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The microscopic labyrinth of passageways bore some resemblance to the tiny galleries dug elsewhere by colonizing bacteria and fungi. Moreover, the tunnel network was connected by a series of linking passages, suggesting endoliths may have lived there.
But the most compelling evidence came from chemical analyses of the samples, which revealed the presence of organic compounds, such as traces of fatty acids and other lipids, probably left behind by microscopic organisms.
In Ivarsson’s opinion, these endoliths found tiny crevices on the surface of the garnets, created by normal wear-and-tear, and used them to slip inside the gemstones. There, they comfortably nestled in, burrowing even deeper to extend their domain.
“Usually, microbes bore and colonize minerals and materials [that are] not so hard as gemstones,” the geobiologist said in a statement.
This is the reason why Ivarsson believes the tiny inhabitants of the garnets had some help getting inside.
“I think there’s a two-step process, a superficial weathering, then an organism takes over,” he pointed out.
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“We suggest that the production of the tunnels was initiated by a combination of abiotic and biological processes, and that at later stages biological processes came to dominate,” the researchers wrote in their paper.
As they explain, “in environments such as river sediments and oxidized soils, garnets are among the few remaining sources of bio-available iron,” which makes it highly conceivable that the microbes moved in to feed on this valuable resource. Whether this happened millions of years ago or in the more recent past remains a mystery, for now.
While no living creatures have been found inside the gemstones at this time, the team plans another expedition to Thailand, to gather biological samples from the same riverbed and see if they can grow the microbes in the lab. If such an experiment yields garnet-chomping endoliths, then their theory will be proven correct.