Moving Rock On Mars! Alien Animal Found, May 2014

Almost thought this could be really good find, but after a second look, it does look like it is an optical illusion. Comparing the rocks on these two pics you can see the rover has moved a few meters between the shots.

http://marsrovers.jpl.nasa.gov/gallery/all/2/n/1833/2N289093752EFFB074P1985L0M1.HTML

http://marsrovers.jpl.nasa.gov/gallery/all/2/n/1843/2N289976994EFFB0EOP0675L0M1.HTML

 

My first thought was parrallax too.  Hard to judge scale - those rocks could be huge as you can't tell how far away they are without any reference like trees or actual animals, although admittedly they do look pretty close to the rover.