Possible Signs of Ancient Drying in Martian Rock Posted on January 18, 2017 by Frank Cisco A grid of small polygons on the Martian rock surface near the right edge of this view may have originated as cracks in drying mud more than 3 billion years ago. via NASA http://ift.tt/2jzvy1d Share this: Share on X (Opens in new window) X Share on Facebook (Opens in new window) Facebook Like Loading... Related