HELP! Can any member tell me what these little grey "onion" shapes are that is growing under this Hammer

[Clive Hill]

I have noticed these onion shaped balls growing under this Blotched Hammer, also have a few popping up on rocks and other coral. can any member tell me what they are? I was told they are micro sponges and will not harm the tank, but I want to be sure.

 

[DaveK]

They are small sponges, sometimes called pineapple sponges. They are harmless and usually considered a good sign that your doing something right.

 

[Clive Hill]

Many thanks DaveK

 

[nanoreefing4fun]

+1 Scypha Sponge (pineapple sponge) to RS ! Start a tank thread and share more pics with us so we can follow along !