There is an alien civilization, many billions of light-years from Earth. This civilization hosts itself on a large rocky asteroid with an artificial atmosphere and artificial gravity. In the past, this rock had been separated into five, with one large in the middle, and the other four orbiting around it. These rocks have relatively flat faces that the aliens have built their cities.
Edits: Each rocky area would comprise of one main city with a limited area of wild-life, think New York City with a small forest right after it. This rocky area would not be formed as a disc, rather a shape much like unformed clay with a slightly rounded, but mostly flat face. (NOT like a cube or, again, disc. Think ball with one part with a smaller radius.) This rock face would have to form naturally. Please note that these are aliens that have evolved to live on this rock. Aliens are to this rock as we are to earth.
So... odd question, but is it possible that an asteroid/planet could form with a 'flat' face, and if so, how would I explain how it was created, other than magic! Also, I don't mean perfectly flat, more along the lines of a low-incline dome. Finally, would it be possible for smaller pieces of it to orbit it, or would that break the whole 'flat' thing.
This is going so well for my first question on this site!