Is this a Sponge

[crazy cajun]

just noticed these growing a few months ago i have several around my live rock just wondering if they are sponges and good or bad?

 

[kbuser92]

Yep, looks like a pineapple sponge.

 

[crazy cajun]

good/ bad ??

 

[kbuser92]

Sorry, forgot to answer that half. They are just filter feeders and come and go. It means therrs excess nutrients in your tank, but as long as thrres only a handful, I wouldn't worry about water quality. If you get a lot, just cut back on feedings and do a couple extra water changes.