Just curious, there is a river close to my house that has dried up leaving all kinds of really neat shaped rocks and things. There is not any harm in putting regular rocks in your aquarium is there? I have ~100 lbs of live rock already but some of the ones down there are really neat looking. I'm not sure exactly what they're made of, but I'd like to put a few in there if it wouldn't hurt anything. Just curious if anyone else has done this, base rock can be expensive when you buy a lot of it.