It would split up. This game's gravity comes only from white/black holes, so you can't really have a good system model. I really wish stuff would sink through water....
Few fun things: Make allot of sand and bomb it, with luck, you`ll get a little sand in orbit that manages to not hit each other. Also, I like to have sand, put a layer inbetween, and have seed, then bomb it and try to get alot of plants. My best is about half the screen covered in it.