I agree, these rocks need to be cleaned before you reuse them, otherwise it would be way too much of the organics just rotting in your tank.
I think there's two basic ways to get to a point where the rocks are usable:
1) Add the rocks to something like a Brute garbage pail, add saltwater, a circulation pump, possibly a heater, and maybe some starter bacteria from a bottle. Then, you let the whole thing "cook" until the bacteria consume the organics, which could take many weeks to months to complete.
2) Add bleach to the same setup as above, and the process will now take a few days to a week or so max, at which time your rocks will look bright white and brand new again. Any residual bleach can be safely neutralized by allowing the rock to completely dry, ideally in the sun (bleach is broken down by sunlight and is neutralized when dry), or by overdosing with a dechlorinator like SeaChem Prime, or by addition sodium thiosulfate (at type of dechlorinator).
I'd suggest looking here for more info on using bleach to cure old rocks:
There are three main methods for curing live rock for a saltwater reef tank: natural, bleach and acid. Our focus today is using bleach for curing dry rock and we answer three direct questions. 1. What is a bleach cure? 2. When is it appropriate to bleach cure rock? 3. How to do
www.bulkreefsupply.com
Last thought is that I don't know how big your tank is or how much rock we are talking about, but you could consider scraping your rock, and starting with new rocks. I'd suggest using some to all real, wet live rock either way you go. Adding real live rock to your system brings with it a lot of benefits.
Good luck!