Authentic NASA Mars Rover image shows extraterrestrial structures, spaceship, on Mars?
Photo is from the Rear HazCam of the Spirit Rover. Posted on the JPL/NASA Website. No official description or explanation that I can see. Very odd.
Another Photo (Source)
A YouTube Video I found on it (Uploaded Today - 12/27/2010)
UFO EXCLUSIVE! Breaking News Clear UFO Base Caught on Cam By Mars Rovers December 2010:
UFO Base on Mars? Bizarre NASA Mars Exploration Rover Photo