If you get cured rock from your pet store, it is ok. The problem with cured rock through the mail is that being out of the water for that long will start the decaying process again. It won't be as bad as uncured rock but you should still cure it to be safe. Uncured rock in my opinion is the way to go. It is cheaper and there is much more life on it. There are websites that sell hand-picked, uncured rock for as little as 3.15 a lb, shipped second day. I ordered 65 lbs of it,cured it for 2.5 weeks and it turned out to be full of life.