By looking at the critter ID, I’m guessing these are pineapple sponges. But I have hundreds of these guys all over.
is it a Pineapple sponge, and is there such a thing as too many?
I try to scrape them off whenever I can but they seem to spread like crazy. They took over several if my corals.
I would have to say yes to Pineapple sponges. They can look unsightly sometimes, but they are a great thing to have in a tank. They usually balance themselves out over time.