WOW! You dont like your friend very much...lol. Just kidding. I've heard that the Sea Apples, when they die, are very toxic and can poison the tank. The Foxface is also poisonous.
Was reading a book last night that cautioned against sea apples as they will eviscerate themselves (turn themselves inside out) as a self defense mechanism. This then Fouls the water and kills the other animals in your tank. Others might have another opinion but I read this in Mariner Aquariums from Beginners to Breeders.
We had a foxface in our reef tank until recently. The foxface never bothered any of our corals. Great fish; but ours was such a pig he would rush in and steal the jawfish's food; which would stress out the blue spots. Our foxface ate nori, flake and frozen foods.