New Growth or Coral?

[raymd]

Hi. I am noticing these new growths or coral in my tank. They showed up recently on a rock with what used to be three large and thriving green mushroom ricordea. The ricordea have shrunk in size over the past two weeks. Thoughts? Thank you.

 

[Macdaddynick1]

Sponge

 

[raymd]

Sponge

Are they harmful?

 

[Macdaddynick1]

No they’re beneficial

 

[kevgib67]

Good filter feeders.