Central Australian salt crystals contain ancient microorganisms that were trapped 830 million years ago, according to new research.
And there is a chance that some of the microorganisms are still alive.
The single-celled organisms are encased in tiny pockets of fluid – smaller than the width of a human hair – in halite, or salt, from a sedimentary rock formation. The microorganisms lived nearly a billion years ago in what was either a shallow, salty marine environment or a shallow, salty lake. Researchers discovered this ancient life by examining the salt crystals using light microscopy, meaning they didn’t disturb the fluid pockets – and the status of the life inside is unknown . However, scientists have previously claimed to have resurrected primitive microorganisms found in salt crystals, so it’s possible the Australian organisms are still alive as well.
Locked in salt
Ancient microorganisms have been found in salt crystals before, with the oldest dating back to the Permian period around 250 million years ago. However, most studies of these crystals are destructive, said study co-author Sara Schreder-Gomes, who conducted the research at the University of West Virginia. In previous studies, researchers extracted the fluids locked inside the crystals with a syringe, or ground or dissolved the crystals to uncover the mysteries inside.
These methods can make it difficult to understand the age of microorganisms inside fluid pockets. For example, some fluid pockets form immediately as the salt crystal takes shape, meaning anything trapped inside is the same age as the crystal, Schreder-Gomes said. Other pockets form later as the fractures in the crystal fill. Once the crystal has been crushed, it is difficult to ensure that the primary and secondary liquid pockets do not mix.
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The new study examined halite from Australia’s Browne Formation, which preserves an ancient salt-rich landscape. The researchers took halite samples from 4,858 feet (1,481 meters) to 4,987 feet (1,520 m) below the modern surface and sliced the halite 0.04 inches (1 millimeter) thick. They then performed a microscopic examination of the halite using both visible and ultraviolet light, magnifying the contents of the pockets of fluid within up to 2,000 times and focusing on the primary crystals that formed. 830 million years ago.
Zombie life and the search for ancient aliens
Inside, the researchers discovered eukaryotes (algae and fungi with distinct cell nuclei) and prokaryotes (bacteria and archaea without nuclei). They distinguished these organisms by their shape, size, color and fluorescence under UV light, Schreder-Gomes said.
Researchers can’t determine the precise species of these microorganisms, even though one looks a lot like Dunaliella, a very common salt-loving algae found in ancient and modern salty environments. Organisms are tiny, ranging from half a micron to 5 microns in diameter. (For comparison, a human hair is about 70 microns wide.)
Salt-loving microorganisms are survivors, able to go dormant or alter their metabolism to stay alive during times when the water around them dries up, Schreder-Gomes said. In 2000, scientists claimed to have revived a 250 million year old bacterium from salt, although they could not definitively prove that their zombie bacteria were not modern contaminants. Other very ancient microorganisms have been resurrected with more certainty, including 101.5 million year old bacteria in seabed sediment. Researchers have not, at this stage, drilled into the crystals to find out if the Australian microorganisms might have a chance of a second life. “If they could survive 250 million years, why not a few hundred million more?” says Schreder-Gomes. “It’s certainly a possibility for the future to try to cultivate them.”
Findings could be used to search for ancient aliens. The Browne Formation rocks formed in an environment similar to the environment that likely existed on ancient Mars, Schreder-Gomes said. The methods the team uses to study organisms could also be used to search for microorganisms long gone from the Red Planet. The Perseverance Mars rover is caching rocks that will eventually be brought to Earth, and nondestructive techniques will be needed to understand the context of these rock formations, Schreder-Gomes said.
“We need to do these kinds of analyzes before any other destructive technique with return samples,” she said.
Originally posted on Live Science