The only really bad thing id say is gorilla crabs. Somewhat easily caught with bottle traps tho. But my porcupine puffer likes them as snacks so i never had to worry. I have both faois rock and tampa bay saltwater rock. My faois rock had 2 aptasia on it (id say aptasia is worse than gorilla crabs if left un treated) it was cured well and the cycle only lasted 6 days. Also had no hitchhikers on it except the aptasia. Tampa bay saltwater rock has no equal comparison. It is exploding with life. Coraline, sponges, feather dusters, barnacles, porcelain crabs, gorilla crabs, hermit crabs, various snails, cup corals, pistol shrimp. And florida rock doesnt have aptasia at all. There is some other type of anemone that is similar to aptasia but larger and non invasive. I have 2 in my predator tank and they were there 3 years ago when i bought the rock. They are actually really nice looking so i never killed them. Ive yet to go into a fish store and find rock remotely comparable to tampa bay saltwaters rock. But like other have said it comes with both good and sometimes bad hitchhikers. Nothing a simple trap and some patience cant handle tho.