white balls on underside of zoa rock Please Help!

[New2reef]

Hi
My Zoa colony has been disappearing. today I found these large white balls on the Underside of the rock ( not on top w the colony). they look much too large for Zoa pox. they are nowhere else in the tank. any ideas at all? please help- this is my first attempt at keeping zoas. thank you so much for any input or ideas!

 

[Ingy]

looks like sponges. I have them in all sorts of dark places ( caves, underside of rocks). They are harmless and wont grow into the lit areas.

 

[Ricksreef]

Agree,they are pineapple sponges.