New polyp or hitchhiker?

[TedsReef]

Hello all. I noticed two of these on a blastos I recently put in my tank. Not sure if it’s a new polyp formation or a hitchhiker. Thanks.

 

[Lovemyreef2015]

Looks like a sponge

 

[TedsReef]

Looks like a sponge

Should I remove them?

 

[DSC reef]

No need, harmless filter feeder. Easily done though if you want too.

 

[TedsReef]

No need, harmless filter feeder. Easily done though if you want too.

Great I’ll keep them around. Would you happen to know the name of this type of sponge so I can research more information?

 

[DSC reef]

I don't know the name of that particular sponge to be honest. I'd start with pineapple sponge or Tethya sp. Family Tethyidae and see where that goes. It's not an invasive sponge though.