Mars's moons, Phobos and Deimos, are not perfectly round. They are actually irregularly shaped, resembling potatoes or asteroids more than the smooth spheres of Earth's Moon.

Here's why:

* Size: Phobos and Deimos are relatively small compared to our Moon. They lack the significant gravitational pull needed to overcome their own internal rigidity and form a spherical shape.

* Composition: They are likely composed of loosely packed rock and dust, further contributing to their irregular shape.

* Formation: They are thought to have formed from captured asteroids, rather than accreting from a disk of material like our Moon, which explains their irregular shape.

While not perfectly round, they are still classified as "natural satellites" because they orbit a planet.