This image, taken by the panoramic camera on NASA's Mars Exploration Rover Spirit during the rover's trek through the "Columbia Hills" at "Gusev Crater," shows the horizontally layered rock dubbed "Tetl." Scientists hope to investigate this rock in more detail, aiming to determine whether the rock's layering is volcanic or sedimentary in origin. If for some reason this particular rock is not favorably positioned for grinding and examination by the toolbox of instruments on the rover's robotic arm, Spirit will be within short reach of another similar rock, dubbed "Coba." Spirit took this image on its 264th martian day, or sol (Sept. 29, 2004). This is a false-color composite image generated from the panoramic camera's 750-, 530-, and 430-nanometer filters.