Mussels or clams on zoa rock?

[Kdog7454]

I purchased this zoa rock from a lfs and after a few weeks i noticed these guys on there. Are they good or bad and should i dispose of them or keep in tank? Thanks guys

 

[AltitudeAquarium]

I purchased this zoa rock from a lfs and after a few weeks i noticed these guys on there. Are they good or bad and should i dispose of them or keep in tank? Thanks guys

They are bivalves which help filter the water. I consider them good. If you don't want them, you can send them to me. Wink