Figure 1 (Click on image for larger view)

This image taken by the microscopic imager onboard the Mars Exploration Rover Spirit shows a close-up look at the rock dubbed "Humphrey." The image was taken after the rover drilled into the rock with its rock abrasion tool, exposing fresh rock underneath. Scientists are examining "Humphrey" for clues to its past with the rover's suite of scientific instruments, located on the rover's arm along with its rock abrasion tool. This image was taken on the 60th martian day, or sol, of Spirit's mission. The rover is on its way to a large crater nicknamed "Bonneville."

Natural or Manmade?
The circled areas in Figure 1 above represent features that scientists have identified as being either natural or induced by grinding processes. The yellow circle shows a natural mark; the green and blue circles highlights droppings thought to be left by the rover's Moessbauer spectrometer; and the red circle contains a natural indentation. The image was taken on the 60th martian day, or sol, of the rover's mission.