Scientists recently identified peculiar micro-burrows in marble and limestone formations in Namibia, Oman, and Saudi Arabia, which may be remnants of an unknown life form. The research was published in the Geomicrobiology Journal.
Geologist Cees Passchier, a professor at Johannes Gutenberg University Mainz, first discovered the unusual structures during fieldwork in Namibia around 15 years ago. "We were surprised. These tubes are apparently not the result of a geological process," Passchier said, according to IFLScience.
These micro-burrows are tube-like tunnels about half a millimeter wide and up to three centimeters long, found in the marbles and limestones of certain deserted regions. The tubes are arranged parallel to each other and extend along the rocks in stripes up to ten meters long, indicating a widespread phenomenon rather than a localized event.
Upon further investigation, the research team found similar structures in Oman's limestone and Saudi Arabia's marble. This suggests that the unknown forms of life in Namibia are not an isolated phenomenon.
The scientists suggest that these micro-burrows were not formed by geological processes but by microorganisms that used the calcium carbonate present in the rocks as a source of nutrients. Inside the micro-burrows, they detected a fine dust residue composed of calcium carbonate, reinforcing the hypothesis that these organisms extracted essential compounds for their metabolism.
"When analyzing samples of the affected rocks, we found remnants of biological material. However, we still cannot determine whether this organism still exists or if it belongs to an extinct species," Passchier stated.
The orderly arrangement of the tubes and the presence of biological material suggest that they are not the result of natural fractures or erosion. The scientists have not yet been able to extract DNA or proteins from the samples. "The problem is that, although we have found traces of biomaterial in the rock samples, we have not been able to extract DNA or proteins that would allow us to identify these organisms with certainty," the research team stated.
These findings raise several key questions: Did an undiscovered species create these tunnels? Could similar life forms still exist in hidden parts of the world? The scientists do not know whether the organisms are bacteria, lichen, fungi, or another form of life.
The broader phenomenon may be linked to a time when the climate was more humid than it is today. "We assume that they were formed in a slightly more humid climate, not in the dry desert climate that prevails today," Passchier stated.
These microorganisms may influence carbon storage and release in Earth's ecosystems. Researchers believe these microorganisms may have shaped the global carbon cycle. "This form of life, of which we do not know whether it still exists, could be important for the global carbon cycle. It is therefore essential that the scientific community becomes aware of it," Passchier concluded.
Endolithic microorganisms are known to thrive in extreme conditions, such as deserts and deep-sea environments, thanks to their ability to extract nutrients from minerals. Microbes that colonize the interior of rocks are known as endoliths, derived from the Greek words for "inside rock."
"We don't currently know whether this is a life form that has become extinct or is still alive somewhere," Passchier added.
These findings suggest that microbial activity in rocks can impact the composition of the environment over long periods. If these organisms were widespread, they could have helped regulate CO₂ levels in various ways. The microorganisms may have played a previously unknown role in breaking down carbonate minerals, influencing the levels of carbon dioxide in Earth's atmosphere.
"These types of interactions between the biosphere and the geosphere could have implications not yet understood in Earth's carbon balance," Passchier added.
The article was written with the assistance of a news analysis system.