While browsing through MOC images for stains I came across this anomaly.

http://ida.wr.usgs.gov/html/m12012/m1201292.html

It has a definite shadow and apparent height.

Lan Fleming had this to say about it..

"..I just checked the support data for M1201292. The sun azimuth is 54 degrees measured clockwise from a line drawn from the center of the image to the right edge of the photograph. I attached a small 2X enlargement to this message (see image below) that shows the line pointing to the sun drawn in next to the object. The long and narrow dark streak is running in nearly the same direction as the azimuth line. So the streak is the object's shadow, all right. No doubt about it. And the object is about 1.4 times taller than the length of the shadow. Pretty neat. However (and there's always a "however" with this stuff), I'm wondering if this could be a dust devil. There are lots of dark streaks all over this image that look like they might be dust devil tracks."

My only question as to it's being a dust devil is the lack of an apparent track or trail to or from it. As well, as can be seen from the photos showing Dust Devils, they are very diffuse with a very light shadow, unlike the artifact under investigation.

This is pending further back up and investigation. I have e-mailed JPL and NASA but I don't expect any response.