I had the same problem with mushrooms in my tank. I shouldnt say had, I should say HAVE.
Feeding them once a week with shrimp or fish is the only way I can keep the remaining 2 alive.
I know some people say they cant stop them from multiplying, in my tank they only survive by getting fed.
I hope this helps.
BTW, once mine turned white they were done. I only was able to rescue the 2 biggest by feeding them while thye were still in good health.