These 2-Million-Year-Old Tunnels Span Two Continents: No One Knows Who Built Them

Geologists have identified extensive microscopic tunnel systems preserved within ancient marble and limestone formations, revealing biological activity dating back up to two million years.

The structures were first documented in the deserts of Namibia and later confirmed across distant regions in Oman and Saudi Arabia, suggesting a phenomenon that once spanned multiple continents.

Researchers describe the discovery as a rare and compelling biological signal embedded in Earth’s geological record, pointing to a previously unknown form of life capable of altering solid rock.

Microscopic Engineering Attributed to an Unknown Endolithic Organism

Professor Cees Passchier and his team identified the tunnels as biologically formed, attributing them to an endolithic microorganism that lived within rock rather than on its surface.

Each tunnel measures roughly half a millimeter in width and extends several centimeters in length, forming dense networks invisible to the naked eye.

While chemical traces of biological residue remain, scientists have been unable to recover DNA, leaving the identity and evolutionary lineage of the organism unresolved.

Dating the Tunnels to the Pleistocene Epoch

Radiometric and stratigraphic analysis of surrounding rock layers places the tunnels between one and two million years old, during the Pleistocene epoch.

The age and consistency of the formations across separate continents indicate a widespread and sustained biological presence rather than isolated or accidental formations.

Despite extensive investigation, no living descendants of the organism have been identified, suggesting it may be extinct or exist in environments yet to be explored.

Implications for Earth’s Carbon Cycle and the Search for Extraterrestrial Life

The findings have renewed scientific focus on bioweathering and carbon cycling, highlighting how microorganisms may have influenced Earth’s geology in ways still poorly understood.

Researchers also view the tunnels as potential analogs for life on Mars, where similar rock based habitats could preserve traces of ancient organisms, expanding the search for life beyond Earth.

Together, these insights underscore the broader implications of the discovery, suggesting that microscopic life can leave lasting, planet-shaping signatures within solid rock. By reshaping minerals, altering chemical pathways, and creating protected subsurface niches, such organisms may act as quiet but powerful agents of planetary change. Understanding these processes not only reframes how scientists interpret Earth’s deep history, but also sharpens the tools used to recognize subtle bio-signatures, whether buried beneath our own planet’s surface or hidden within the rocks of distant worlds.