Go to a bookstore and buy a book (ANY book) on creating and maintaining marine aquariums, the book will answer most, if not all, of your questions.cara said:No, they are still in the tank and have never been in the air except for the ten seconds it takes to quick dump them in the tank. They are no longer "slimy". Not that they are super slick but they don't seem to have anything growing on them. I don't know, my cleaner shrimp has moved onto better and newer rocks. Could it have cleaned them off?