Contents

13 March 2009
Vol 323, Issue 5920

About The Cover

Cover image expansion

COVER False-color scanning electron micrograph of oriented vaterite, a crystalline polymorph of calcium carbonate, formed through template-controlled nucleation. Formation starts with the aggregation of prenucleation clusters forming an amorphous phase from which the crystals develop at the template surface. This experimental process may be analogous to the natural formation of seashells and other marine skeletons. See page 1455. Image: W. J. E. M. Habraken and C. J. van den Hoogen/Eindhoven University of Technology