This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA’s Mars rover Curiosity on Sol 1450 (2016-09-04 01:26:01 UTC). Green arrows at upper right point to a boulder-sized artificial rock. It is shaped like a box, with two large flat sides meeting in 90 degrees. Its bottom was fractured. The fracture exposes its internal structure (red arrows). If the object is a natural rock instead of an artificial rock, there should not be such difference in the surface features of the object. Image source: mars.nasa.gov/msl/multimedia/raw/?rawid=1450MR00718203407…