i should have mentioned this before, but when searching for live rock, you should look for the lightest, most porous pieces available. the more surface area the rock has, the better. inside the rock there are also areas that are practically void of oxygen where anaerobic bacteria live, and these bacteria convert nitrate to nitrogen gas. with super dense rock, there isn't going to be a lot of this bacteria present.
now you have this rock, so i would say to take the bottom piece out of the tank, wrap it in a towel, and whack it with a hammer. the towel is so it doesn't shoot all over the bedroom. then try to make a more natural looking aquascape.