What you're seeing is Diatoms and is extremely common in a new tank. They will eventually go away on their own. The mushrooms might, or might not make it through the cycle. It looks as if you have cured live rock since you have corals attached to them, so I'm going to say, that they really might make it through. Keep an eye on parameters. You might not see a huge spike like people who start with uncured rock will see when they cycle a tank.