This image was taken by Mastcam: Left (MAST_LEFT) onboard NASA’s Mars rover Curiosity on Sol 1089 (2015-08-30 01:00:25 UTC).
Also, on the full image, you will also be able to find THIS:
Now, I don’t take credit. Other people have found this before I did. But it’s quite interesting, don’t you think?
Edit: I was actually able to find the original link! Here: http://mars.nasa.gov/msl/multimedia/…500151E01_DXXX