Altiarchaea are carbon-fixing microbes and targets of multiple viruses in Earth's deep subsurface. They are abundant representatives of deep subsurface ecosystems. A team of researchers described how the viruses repeatedly attempted to infect and destroy the host archaea—and how the microbes resist. The battle waged below the Earth's surface is reconstructed by combining a study of microbial communities (metagenomics) and a chemical labeling approach.