Recently, space image processing enthusiast Thomas Appéré noticed that Curiosity had taken five photos of exactly the same spot on the rim of Gale crater, identical but for being taken at different times of day. That spot was due north of the rover, so the rising and lowering Sun illuminates the rounded hummocks of the crater rim differently from early morning to early afternoon. It's winter in the Martian southern hemisphere, so the Sun is north of the rover, slightly shadowing rover-facing slopes. Here, Appéré has stacked the five images and animated them:
The animated GIF format posterizes the color, so to help you better appreciate the shifting shadows I made a "before-and-after" comparison of two of them. Appéré posted these and one more of the images in full resolution and color on his Flickr page.
They're pretty enough to be a painting!