Geologists documented microscopic tunnel networks in ancient marble and limestone across three desert regions, underscoring a widespread biological signal.
Identified by Professor Cees Passchier as biologically formed by an endolithic microorganism, these microbial tunnels were first seen in Namibia and later confirmed in Oman and Saudi Arabia. Radiometric and stratigraphic dating of surrounding rock place them at 1–2 million years old in the Pleistocene.
Measuring about 0.5 millimeters wide and several centimeters long, the structures retain biological residue but no recoverable DNA, leaving the organism unknown. The findings focus new collaboration on bioweathering, carbon cycling, and potential analogs for life in rock on Mars, while noting that no living specimens have been found.
