Heavy-metal mines might be a tough environment to grow up in, but many microbes call them home, including viruses. A recent look at core samples from a lead and zinc mine in China revealed how viruses fit into this extreme ecosystem. Environmental factors like acidity appeared to play a big role in shaping viral communities. High acidity tends to make environments less hospitable, even for organisms that live in extreme places. That explains why less acidic (higher pH) core samples contained more viruses. Similarly, viral gene function varied with depth. Deeper and less environmentally extreme layers contained genes with conventional functions related to metabolism and structure, while surface layers largely contained genes of unknown function. Tests also detected genes that viruses might use to get their bacterial hosts to incorporate sulfur from mine runoff. That suggests that viruses in these areas could help prevent the buildup of harmful sulfur, making life a little more bearable in these extreme environments.