Moons often have interesting features, some have a massive one
This picture is of Mimas, a moon of Saturn. This picture was taken by the Cassini spacecraft using its narrow-angle lense, which focuses on wavelengths of ultraviolet at around 338 nanometers.
The most striking feature on the moon is the massive crater, which is over 130 kilometers wide. It nearly stretches around one third of the diameter of the planet. The mountain is almost as tall as mount Everest here on Earth.[1][2]
Asteroids smash into moons all the time. Unlike Earth, the craters do not erode away. This is because there is no atmosphere and no molant core on most moons. This means that the wind or water can not erode it and there is no plate tectonics to melt and “renew” the surface. This means that the craters on the surface are often the legacy of the entire life of the moon.