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Microorganisms, Perhaps Still Alive, Discovered In 830-Million-Year-Old Rock Salt


Tom Hale

Senior Journalist

clockMay 16 2022, 16:31 UTC

Is anybody there? Fluid inclusions in a sample of halite, potentially containing ancient microorganisms. Image credit: Courtesy Sara Schreder-Gomes.

Trapped in an 830-million-year-old rock salt crystal, scientists have discovered the potential remnants of prokaryotic and algal life which they say may – just may – still be alive.

Scientists used a selection of imaging techniques to discover well-preserved organic solids locked within fluid inclusions embedded in an ancient piece of rock salt, as known as halite. Reporting their findings in the journal Geology, the team argues these objects bear an uncanny resemblance to cells of prokaryotes and algae, as well as the organic compounds they can produce. 


The sample of rock salt is estimated to be 830-million-years-old and was obtained through core samples taken from within the Neoproterozoic Browne Formation in Australia at a depth between 1,480 to 1,520 meters (4,855 to 4,986 feet).

Crystalized rock salt is not capable of sustaining ancient life by itself, so the potential microorganisms are not simply locked within the crystals, like an ant trapped in amber. As rock salt crystals form through the evaporation of salty seawater, they can trap small amounts of water and microscopic organisms in primary fluid inclusions. Within these tiny pockets of water, the researchers identified the possible microorganisms and organic compounds.

Most intriguing of all, the study authors raise the possibility that these microorganisms may still be alive. Looking at previous examples of microorganisms found in halite samples, the team speculates that organic matter within the Browne Formation halite may possibly have entered a dormant and suspended state, but could still potentially be considered alive. 


“Are microorganisms in Browne Formation halite alive?” the study authors ask.

For one, the samples have not undergone any significant decomposition and are able to be easily recognized despite hundreds of millions of years passing. They also point toward a previous study that found microorganisms living within fluid inclusions locked within 150,000-year-old rock salt. There was even one study, published in Nature in 2000, which documented living bacteria within a similar 250-million-year-old salt crystal, they note. 

Based on this, the researchers add: “it is plausible that microorganisms from the Neoproterozoic Browne Formation are extant.” 


If this is true, it could hold some big implications for the search for extraterrestrial life. It’s known that the surface of Mars, once home to vast salty lakes of water, features some geology that’s potentially similar to the Browne Formation halite. If life is able to linger within Earth-bound halite, then who’s to say it can’t within a Martian sample?

“Microorganisms that may have existed in surface brines on Mars in the ancient past may be trapped as microfossils in chemical sedimentary rocks,” the study concludes. 

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