Biocrusts over Head (IMAGE) Arizona State University Caption The desert outside Chandler, Ariz., shows a darkening of the biocrust (left) over its surface. Credit Ferran Garcia-Pichel, Arizona State University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.