Researcher collects cores of biocrust (IMAGE) Penn State Caption Penn State graduate student Ryan Trexler collects cores of biocrust from the field before bringing them back to the lab to study. Credit Penn State Usage Restrictions Credit must be given to the creator. Only noncommercial uses of the work are permitted. No derivatives or adaptations of the work are permitted. License CC BY-NC-ND 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.