Image Source - http://mars.jpl.nasa.gov/msl-raw-images/msss/01077/mcam/1077MR0047360000600159E01_DXXX.jpg
This is one of the unique Stones on Mars. It resembles Human Face. NASA nothing says about it specially.
NASA said: This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1077 (2015-08-17 17:16:55 UTC).
Image Credit: NASA/JPL-Caltech/MSSS
Image Credit: NASA/JPL-Caltech/MSSS
Other Latest Images of Mars. Click on Imags to see that in Zoom-in Mode.