This real-time movie shows the light activated motion of the self-propelled particles (diameter D = 2:2m). The hematite cube is visible as the darker spot on the particles. When the blue light is shut, the particle exhibits random thermal motion, when the light is on the cube faces the cell surface and exhibits an active motion. The propulsion stops when the light is shut. This video relates to a paper that appeared in the Jan. 31, 2013, issue of Science Express, published by AAAS. The paper, by Jeremie Palacci at New York University in New York, N.Y., and colleagues was titled, "Living Crystals of Light-Activated Colloidal Surfers."