A Mars Curiosity image of a “rock circle” has appeared in the British tabloids in the last few days, touted by “alien hunters” to be an artifact of some kind .
The NY Post gave secondary coverage and carefully stated that it was “recently found” among the images by said “hunters.”
From the setting, I could see that it did not match the recent terrain being covered ( we’re up to sol 1734, ) and I did spend a little time looking back over the route to find a likely spot. I was pretty lucky, although I will credit my intuition, as I found it as a Mastcam image from sol 528
In fact, this image was evidently not a chance acquisition, since they immediately acquired this followup image, also on sol 528
Here we get a more detailed view, and it looks somewhat more “natural”, I think, with noticeable irregularities. Then, on sol 529, they actually “moved in for a look” and acquired this image
Here you can start to get an idea of its formation. It seems to be sort of a disk with the center scoured low, like a lozenge. Of course, this is just one small feature! From what I understand, the landscape as we see it is formed almost exclusively by very slow erosion from the dust storms.
BTW, the images were acquired on 2014-01-30 13:53:37 UTC, 2014-01-30 13:54:26 UTC, and 2014-01-31 15:46:03 UTC, over three years ago.
Also, here is the section of the path showing the location