Two miles below the Pacific Ocean, scientists have discovered something impossible: rocks that generate electricity and produce oxygen without sunlight. These ancient metallic "batteries" could be the original source of Earth's oxygen - before plants or algae existed. The CIA has known about these rocks since the 1960s, keeping their true potential classified for decades. The discovery dramatically expands where alien life might exist, from billions of possibilities to trillions. These seafloor nodules host thousands of newly discovered species that evolved to harness electricity directly. But now, deep-sea mining threatens to destroy in days what took millions of years to form. Dark Oxygen forces us to reconsider our understanding of life on Earth and beyond. Could disrupting this hidden electrical network trigger the next mass extinction?