17 February 2012
Vol 335, Issue 6070

About The Cover

Cover image expansion

COVER Orbulina universa, a planktonic foraminifera captured live from surface waters off Santa Catalina Island, California. Symbiotic dinoflagellates inhabit the calcite spines (length ~2.5 millimeters) radiating out from a spherical calcite shell (diameter ~0.5 millimeters). After four weeks, the shells sink to the sea floor and become part of the deep-sea microfossil assemblage. The geochemical compositions of these fossils are used to reconstruct past changes in seawater chemistry (see page 818). Photo: Howard J. Spero, University of California, Davis