AA - if it smells then that means there is die off on it. This can cause ammonia spikes, and if you have fish and inverts in the tank then you will want to re cure the rock seperate from your main tank.
This could involve water changes while it re cures itself, until the bad smell goes away. Use a protien skimmer if you can on the cure tank, tub, bucket,... whatever you use. Keep it heated and use a powerhead.
When your done it should only smell like fresh sea water.
Thomas