When oceanic and continental plates collide, one plate is pushed down, or subducted, into the mantle and the other plate is pushed up and studded with volcanoes. This opens the possibility for discovering previously unknown types of biological interactions occurring with deep plate tectonic processes. An interdisciplinary and international team of scientists has shown that a vast microbial ecosystem primarily eats the carbon, sulfur, and iron chemicals produced during the subduction of the oceanic plate beneath Costa Rica. The team found that this microbial ecosystem sequesters a large amount of carbon produced during subduction that would otherwise escape to the atmosphere. “This work shows that carbon may be siphoned off to feed a large ecosystem that exists largely without input from the sun’s energy.