In some of southern Africa’s driest deserts, rocks hold hidden signs of ancient life. Fine, parallel tunnels cut through marble and limestone in Namibia and the Arabian Peninsula. These tunnels are tiny, less than a millimeter wide, and form neat bands stretching meters. They do not match common erosion or geological patterns. Researchers say they come from microbes that bored into rock long ago. Chemical tests show mineral changes and traces of degraded biological material inside tunnels. The tunnels follow fractures but cut into solid rock, something normal weathering cannot explain. These microbes likely lived inside rocks when climate conditions were different, allowing life in harsh deserts. Today, these hyperarid regions have little biological activity. Scientists believe these microbial borings shifted carbon cycles by interacting with carbonate rocks. This discovery also helps in searching for life signs on Mars, where similar rocks exist. The tunnels end quietly in cracks, holding mysteries of ancient desert life waiting to be explored.