Potentially Alive 830-Million-Year-Old Organisms Found Trapped in Ancient Rock - ScienceAlert
A team of geologists has just discovered tiny remnants of prokaryotic and algal life – trapped inside crystals of halite dating back to 830 million years ago.These are called fluid inclusions, and they're remnants of the parent waters from which the halite crystallized.
In addition, microorganisms have been documented in fluid inclusions in gypsum and halite, mostly modern or recent, with a handful dating back to ancient times.However, the method of identifying these ancient organisms has left some doubt as to whether they are the same age as the halite.
They used transmitted-light and ultraviolet petrography, first at low magnification to identify halite crystals, then at up to 2,000x magnification to study the fluid inclusions therein.Some of the samples showed colors consistent with organic decay, while others demonstrated the same fluorescence of modern organisms, suggestive, the researchers said, of unaltered organic material.
Additionally, microorganisms may survive in fluid inclusions by metabolic changes, including starvation survival and cyst stages, and coexistence with organic compounds or dead cells that could serve as nutrient sources.".