Naw, you dont cut mushrooms. leave them where they are and if u add more water flow they soon start to "droop". This means that the mushrooms will start to sag and look like they are melting when in fact they are drooping to "bud" to form new mushrooms. So if you place a few pieces of rock around and underneath the mushroom rock you will collect the offspring of the mushrooms. dont cut the mushrooms , you will only kill them and you cant only cut some types of corals. Mushroom polyps are not one of them.