No, not sure how long the tank has been up but sponge growing everywhere is a good thing and sign of a mature tank. If it were the pineapple sponges I would suggest that you have a silica issue in the tank but since it is of the yellow variety you are good. I have the same stuff growing all inside of my glove polyp colony.if you really don't like it, I'm sure you can get a angel that will devour it. My emperor ignores mine all together