Unseen out in the ocean, countless single-celled organisms grow protective shells to keep them safe as they drift along, living off other tiny marine plants and animals. Taken together, the shells are so plentiful that when they sink they provide one of the best records for the history of ocean chemistry. Oceanographers at the University of Washington, the University of California, Davis and the Pacific Northwest National Laboratory have used modern tools to provide an atomic-scale look at how that shell first forms.