This composite image was taken by the Stardust probe's navigation camera during its encounter with Comet Wild 2 in January. Several large depressed regions and jets of dust and gas can be seen. Comet Wild 2 is about 3.1 miles (5 kilometers in diameter.
Looks like a piece of a moon or planet from the early solar system, blown apart or smashed apart by a long done impact. But then, I'm convinced an orbiting moon or piece of a Mars moon slammed into Mars long ago, so don't take my speculations as worthy.
