Pushing Through Sand (IMAGE) Massachusetts Institute of Technology Caption The photograph shows a square-shaped 'intruder' plunging through various material, including coarse, salt-like grains (white) and fine sand (blueish green), as well as more viscous (green) and pasty (blue) materials. Credit Photo: Felice Frankel Usage Restrictions Images are made available to non-commercial entities, press and the general public under a Creative Commons Attribution Non-Commercial No Derivatives license. You may not alter the images provided, other than to crop them to size. A credit line must be used when reproducing images. 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.