This magnified view of a rock surface inside "Endurance Crater" combines four frames taken by the microscopic imager on NASA's Mars Exploration Rover Opportunity during the rover's 142nd martian day, or sol, on June 17, 2004. This patch of rock is in a region of contact between a layer of rock corresponding to bedrock that Opportunity examined earlier at "Eagle Crater" and the next-lower layer. The area imaged is about 6 centimeters (2.4 inches) on each side.