This set of images compares rocks seen by NASA's Opportunity rover and Curiosity rover at two different parts of Mars. On the left is Wopmay rock, in Endurance Crater, Meridiani Planum, as studied by the Opportunity rover. On the right are the rocks of the Sheepbed unit in Yellowknife Bay, in Gale Crater, as seen by Curiosity. The rover's first drilled rock revealed signs of a past habitable environment.