Live Rock in a Bucket

I was given a 5 gallon bucket of live rock. The bucket is full of live rock and aquarium salt water, and has been sitting in a guys basement for 3 months with a lid on it. I took the lid off and about gagged from the sulfur smell. He said that he never changed anything, it just sat in his basement for 3 months with a sealed lid, he forgot about it. Is the rock cooked, ruined? or what is my next step? I would like to add some rock to my tank to build up one side for corals to sit on.



Is this rock ok, to use? or does it need to be dried out and start over?