[Van down by the river]

I agree with teevee,
Even "cured" rock can cause ammonia spikes although they are substantially less drastic than uncured rock. Personally It is beyond me why anyone would want "KILLED", I mean"cured" rock. Unless you plan to add large amounts of rock all at once, or you want to add inverts right away, "cured" rock has few advantages IMO.

I personally would Not consider this rock Ultra Premium.

It looks like basic "cured/killed" standard Fiji rock.

Only a little coraline algae seperates this from base rock(the lowest grade).

The idea behind "cured" rock is that it is "cycled" in a dark tank to remove dead or dying organisms to prevent ammonia spikes, algae blooms, etc. Does this work?
Yes it does, unfortunately many of the desirable organisms that have survived, have also been killed in the curing process by ammonia, and poor water flow.
Too often a store receives beautiful rock, and proceed to place it in a cramped tank with inadequate filtration for the heavy bioload of new live rock as well as insufficient circulation due to the restrictive hydronamics of a aquarium full of live rock. Not to mention the often lack of proper lighting. Most stores I've seen have their live rock in a overfilled tank, with minimal water movement and little if any lighting. There is no pre-cleaning process or extra efforts to "save" any organisms. It goes straight from the box to the holding tank. People worry about fireworms, well with all the dead and decaying matter it's a breeding ground!
Yes, I know it's more work but there is allot that could be done to improve this process. Without proper care of the rock, many organisms are unnecessarily lost.

What do I suggest? If possible buy smaller amounts of "uncured" rock more often. Buy it from the shipping box or shortly after it arrives. Take it home and thoroughly rinse it in a bucket of saltwater and manually scrub/cut any "iffy" dead or fouling organisms.
cut off outer tissue of sponges as you have a better chance of it recovering. If the outer exposed sponge is dying it will foul and kill any living tissue underneath it. The same goes for most algae. If you trim back the rotting plant, the base which is often still alive will recover. I believe this way sponges, mussels,clams, crabs, shrimp,and worms that are freed from fouling and have clean oxygenated water have a much better chance of survival than being dumped in a silt choked ammonia bath.
If the rock is really smelly, use a powerhead and/or an old magnum/canister type filter and change the water a few times over 2-3 days in the bucket. This should improve even some of the worst rock. I believe your effort will be worth it.

Or you can buy expensive boulders that have sat for weeks or months in a dark stagnant aquarium full of diatoms, covered in the silt and sediment of the dead animals you were trying to get in the first place.