What is this? It can't be good!

[AlyHarper]

Hey yall, looks like I have something growing on my Polythoa... I can't imagine it is a good guy, can anyone identify and recommend treatment?

 

[G Santana]

Sponge Bob Is making his home there.
Pineapple sponge, harmless and will with time go away.

 

[AlyHarper]

So it's not hurting my coral? Great! I appreciate your help!