From all the stuff people on here have told me, if it is mail order rock, then it will still need to be cured again. You will have some die off so this could cause an ammonia spike that could hurt your fish. You should re-cycle it again in a separate container after getting it. There is a write up in the articles section for this.
If you are getting it locally and it never comes out of water, it might be OK. I am not sure if there would be any other concerns with this though.
*180 gal Display, 100 gal basement sump, 33 gal refugium, 3x250 MH, 2x160 VHO actinics, zoos, some softies, LPS & lots of acros and other SPS.
*100 gal prop tank plumbed into main system w/ 2x96 PC lights and 1x150 MH,