Does anyone know what’s this white fuzz?

[HashyReefer]

I have these little fuzzy white growths under my acan. What could it be?

 

[Dread Pirate Dave]

Those are pineapple sponges. Harmless filter feeders.

 

[HashyReefer]

Those are pineapple sponges. Harmless filter feeders.

Thank you!

 

[Lelegance]

Harmless unless they are starting to grow on a coral’s skeleton and irritating it into recession. Where yours are is fine, i have seen some pop up right in between polyps on a favia, that is a no-go.