New research sheds light on carbon-cycle process in areas of the ocean without oxygen. With no dissolved oxygen to sustain animals or plants, ocean anoxic zones are areas where only microbes suited to the environment can live. “You don’t get big fish,” says Morgan Raven, a biogeochemist at the University of California, Santa Barbara. “You don’t even get charismatic zooplankton.” But although anoxic oceans may seem alien to organisms like ourselves that breathe oxygen, they’re full of life, she says. These strange ecosystems continue to expand thanks to climate change, a development concerning to fisheries and anyone who relies on oxygen-rich oceans. But what piques Raven’s interest is the changing chemistry of the oceans—the Earth’s largest carbon sink—and how it could move carbon from the atmosphere to long-term reservoirs like rocks.