The image was one of many returned by the European Space Agency's Mars Express probe of the planet's heavily cratered southern highlands, an ESA release said Friday.
The unnamed elongated crater is about 48 miles long, opens from just under 6 miles wide at one end to 15 miles at the other, and is more than a mile deep at it deepest point.
Impact craters are generally round because the projectiles that create them are driven deep into the ground before the shock wave of the impact can explode outwards, researchers say.
At the elongated crater, the surrounding blanket of material thrown out by the impact, known as the "ejecta blanket," is shaped like a butterfly's wings with two distinct lobes, suggesting at least two projectiles, possible halves of a once-intact body, created the crater, scientists say.
The formation of such elongated features is not over, researchers say; the martian moon Phobos will plow into the planet in a few tens of millions of years, breaking up in the process and likely creating new elongated craters across the planet's surface.