What planet does the moon Phobos belong to?

Phobos is the larger of Mars' two moons and is 27 by 22 by 18 km in diameter. It orbits Mars three times a day, and is so close to the planet's surface that in some locations on Mars it cannot always be seen. Phobos is nearing Mars at a rate of 1.8 m every hundred years; at that rate, it will either crash into Mars in 50 million years or break up into a ring. Its most prominent feature is the 6-mile crater Stickney, its impact causing streak patterns across the moon's surface. Stickney was seen by Mars Global Surveyor to be filled with fine dust, with evidence of boulders sliding down its sloped surface. Like Earth's Moon, Phobos and Deimos always present the same face to their planet. Both are lumpy, heavily-cratered and covered in dust and loose rocks. They are among the darker objects in the solar system.