NASA’s Perseverance rover has made a mysterious discovery during its exploration of Jezero Crater: a dark-colored stone with unusual features that “may have originated from elsewhere.” The unexpected discovery, which the Perseverance team has dubbed “Skull Hill,” was made last week while the intrepid rover continued its descent down the lower part of Witch Hazel Hill along the crater’s rim. At one point, the rover stopped at the boundary between a pair of distinct rock outcrops of contrasting coloration that were first revealed in orbital imagery of the crater. The intriguing location, which the Perseverance team had nicknamed “Port Anson,”...