https://www.cnet.com/news/nasa-spots-mars-meteroid-wild-dark-avalanche/

It looks like the shadow of a comet or a splash of dark paint dragged across the landscape. It looks out of place. NASA's Mars Reconnaissance Orbiter captured a view of Mars showing an impact crater and its unusual aftermath. 

The crater itself is visible as a fuzzy, round area with a slash of dark material leading away from it. This black area is a slope streak, the result of an avalanche triggered by the impact of a meteoroid. "Slope streaks are created when dry dust avalanches leave behind dark swaths on dusty Martian hills," says NASA.