Mark Lever, Aarhus University (image) Aarhus University Caption Mark Lever, Aarhus University, works under sterile conditions in the laboratory. Familiar tools such as a hammer are necessary for a geomicrobiologist working with rock samples from the oceanic crust. Credit Photo: Jesper Rais, AU Communication. Usage Restrictions Photo credits: Jesper Rais, AU Communication. 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.