Geologists recently recorded bands of perfectly parallel millimeter-scale tunnels carved into solid marble or limestone, a pattern that cannot be explained by known geological processes.
If biological in origin, this tunnel would be the first known example of an organized structure. rock-This kind of boring pattern on ancient stones.
tunnels lined up
In the marble and limestone outcrops that span Namibia, Oman, and Saudi Arabia, tunnels appear to run in the same direction in tightly aligned columns, stopping abruptly at fracture surfaces.
Professor Cise W. Passier of the Johannes Gutenberg University Mainz traces back the rock sequence (JGU Mainz) documented how each band begins along the fracture and extends medially as a set of equally spaced tubes.
every tunnel They never intersect or diverge, remaining strictly parallel to neighboring rocks, even if the surrounding rocks fold or crack over time.
This unusual order precludes normal cracking and weathering, raising the central question of whether only biological processes could produce such disciplined patterns.
stone structural pattern
The researchers called the features microburrows, which are small tunnels carved into the interior of the rock, and reported that they can be up to about 1.2 inches (3.05 centimeters) long.
parallel fracture In the case of airplanes, these bands could extend about 33 feet (about 10 meters) and were later exposed to the surface through erosion.
Viewed from above, the openings looked like evenly spaced pores, with none of the tubes splitting, crossing, or joining together.
Since jagged cracks usually branch and intersect, tube set refers to a hard and unusually controlled process. stone.
Rim chemical reaction
White calcium carbonate often filled the tunnels, and nearby rocks sometimes contained calcrete (hard calcium deposits formed by groundwater).
Under a microscope, the edges of the burrows retained a thin outline rich in phosphorus and sulfur, two elements common to cells.
Fluorescence and Raman spectroscopy, laser methods that read molecular vibrations, also found concentrations of carbon-rich material along the edges of the burrows.
“Fossils are too old to preserve DNA or proteins,” Passier wrote, setting strict limits on what the team could recover.
Microorganisms in desert rocks
Scientists have recorded this across the Atacama Desert in northern Chile. inner stonemicroorganisms that live inside rocks for protection.
Some of these organisms can extract energy and nutrients from them. mineral By releasing an acid that dissolves some of the carbonate rock.
Microorganisms that drill through rock typically leave rough, irregular holes, so new tunnels look different from familiar endolithic traces.
This discrepancy suggests that the tunnel bands reflect unusual behavior, or perhaps rare organisms, rather than a familiar rock-dwelling lifestyle.
Signals that lead to growth
One possible driver is chemotaxiscell movement induced by chemical signals in the surrounding environment.
As nutrients seeped through the moist cracks, microbes could have crawled along the gradient, always moving in the direction of richer chemistry.
Crowding forces each colony to keep their distance, leaving straight, evenly spaced paths instead of overlapping each other in a messy manner.
Without a living community to monitor, the idea will remain tentative until lab-grown microbes can carve similar tubes into stone.
ancient waterway
Without a thin membrane, microorganisms cannot penetrate dry stone, so liquid water had to reach the interior of the rock.
Past rains may have caused seepage in the cracks, giving the organisms a starting line and a steady supply of chemicals.
Evidence from Namibia suggests that this belt formed more than a million years ago, long before it was finally opened up by erosion.
The dryness of today’s desert may explain why the tunnels appear abandoned, leaving only traces of mineral fillings and chemicals.
Why the rows remain parallel
Each tube was much wider than a single microbial cell, so the makers probably worked as a community rather than drilling alone.
As that community dissolves the surrounding carbonates, nearby rocks lose readily available nutrients and a growth-inhibiting buffer is created around all tunnels.
The microscopic ring-like structures along some walls grow outward over time and retreat when food becomes scarce.
If experts can link these rings to known groups, the tunnels could become biosignatures, or symbols of life. pattern It suggests a past life.
Biological testing
Finding life means tracking down newer examples, where the tunnels are still sealed within the rock and haven’t changed much.
The JGU Mainz team is now using high-resolution imaging and chemical maps to determine whether any cell-like structures remain at the rim.
Even if genetic material is lost, older samples can reveal patterns in carbon and other elements.
Until these lines of evidence are gathered, the tunnel will be placed in the cautious category. That is, it is suggestive, but not yet assigned to a species.
Identification of such structured micropores would not only reshape our understanding of Earth’s deep biosphere, but also refine the way scientists search for life elsewhere.
Lessons from spacecraft missions
Mars exploration continues to return to subterranean thinking because rocks block radiation and can retain traces for years.
a deep biosphere – Life that lives far below sunlight can survive through chemical reactions in water-filled rocks and sediments.
If the microscopic holes prove to be biological, it would show another way for underground organisms to reshape rocks into readable patterns.
This kind of signature could help the rover team determine which drilled cores on Earth deserve the most careful follow-up.
A place where stories connect
This series of small stone tunnels has driven geologists and microbiologists to the same challenge: determining whether life has patterned itself.
Even without DNA to test, evidence shows that rocks can preserve organized traces for millions of years, which is beneficial.
This research Journal of Global Microbiology.
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