There's Life Inside Earth's Crust

Credits Karen G. Lloyd is the Wrigley Chair in Environmental Studies and professor of Earth science at the University of Southern California. This essay is adapted from her forthcoming book “Intraterrestrials: Discovering the Strangest Life on Earth” (Princeton University Press, 2025). The way to spot a cold methane seep on the ocean floor is to look for the life that gathers around it, like antelopes at a savanna watering hole: clams, mussels, crabs, shrimp, fish, sea anemones and creepy, otherworldly worms. These seeps, exposed by movements of tectonic plates or other geological processes, allow ancient, deeply buried methane to burble through the Earth’s crust and into the water column, where it becomes a kind of manna from heaven — a highly energetic food in what is otherwise a barren desert. Single-celled microbes eat the gas; the crustaceans, worms and other creatures in turn eat the microbes. For microbiologists like myself, this motley crew of creatures is a precious sight, bu ... Read full article.