I thought moons & planets always appear generally round from a distance. This lumpy irregularly-shaped Phobos looks like an asteroid.

Both Mars’ moons (Phobos and Deimos) are asteroids. They’re really small.

“Hydrostatic equilibrium” is the term (I think) for when a body is massive enough for it’s gravity to pull it into a spheroid. E.g. Ceres is about 950km in diameter and is ‘round’.