NASA's Mars Exploration Rover Opportunity examined a boulder called "Wopmay" before heading further east inside "Endurance Crater." The frames combined into this false-color view were taken by Opportunity's panoramic camera during the rover's 251st martian day (Oct. 7, 2004). The coloring accentuates iron-rich spherical concretions as bluish dots embedded in the rock and on the ground around it. The rock is about one meter (3 feet) across. The slope of the ground and loose surface material around the rock prevented Opportunity from getting firm enough footing to use its rock abrasion tool on Wopmay. Evidence from the rover's spectrometers and microscopic imager is consistent with a possibility that rocks near the bottom of the crater were affected by water both before and after the crater formed. The evidence is still not conclusive.