Are these some kind of sponge?

[tobster]

Noticed several of these on the bases of my hammers and octospawns? Any ideas? Good or bad?
Thanks

 

[WalkerLovesTheOcean]

Yes, those are pineapple sponges. They are filter feeders and do no harm.

 

[tobster]

Yes, those are pineapple sponges.

Are they ok to leave alone? I didn’t realize they got that big.

 

[WalkerLovesTheOcean]

Are they ok to leave alone? I didn’t realize they got that big.

You might want to remove them so they don't cause irritation to the coral, but because they're on the skeleton they can stay.