Anybody want to speculate on what this is?
I spotted the item and it looked out of place in the image. I blew up the thing that looked out of place, and it looks like a hole in it. I'll be the first to guess, a rock with a hole in it.
Right Panoramic Camera Non-linearized Full frame EDR acquired on Sol 45 of Spirit's mission to Gusev Crater at approximately 13:32:57 Mars local solar time, camera commanded to use Filter 1 (179 nm). NASA/JPL/Cornell