Originally Posted by Andrew McFadden
Live rock is just rock that is cured and will have beneficial bacteria along with maybe some crabs and what not living in it. All rock that I know of is not real anymore because its against the law to take rock from a living coral reef. If you bought dry rock it needs to go in now. If you bought rock from an established tank that has a good growth of things I'd wait till its all done being cycled. If you have rock that has no growth on it it wouldn't hurt and only help. The best thing to do is ask the lfs
you got or are getting it from. Because the one I use to use cured their own rock in the back. Doing that I would put it in now.
Hope this help you understand
Actually, live rock collection is only illegal in some parts of the world. A lot of times dealers will tell you where it's from (e.g. Tonga). Live rock itself is basically coral skeletons that have broken off the reef and become a harbor for beneficial bacteria as well as some other life forms (sponges, other coral, algae, etc.).
There is artificial rock and dry rock as well. The advantage here is there are no unwanted hitchhikers and no reef environment is harmed. (My understanding is that natural dry rock is essentially mined from where the sea used to be.)
"Curing" is basically giving natural live rock time for the stuff that's going to die anyway to die and not pollute a display tank.
Pretty much the remainder of what Andrew said is right on.
Dry rock can go in pretty much anytime. Uncured rock goes in during cycle only, and cured rock goes in at the beginning or end of the cycle, but not during.