This image was taken by the microscopic imager, an instrument located on the Mars Exploration Rover Opportunity's instrument deployment device, or "arm." The image shows the imprint of the donut-shaped plate on the rover's Moessbauer spectrometer instrument, also located on the "arm." The Moessbauer spectrometer was deployed within the trench to investigate the fine-grained soil for iron-bearing minerals. The area in this image measures approximately 3 centimeters (1.2 inches) across.