ID..feather duster?

[reynaldoramon]

So my blues came on this evening and I noticed these guys. See 5 of them . Never noticed them before. They look like fat feather dusters. I took better pics with a regular camera if need be. Tank is about 6 months old now. There ia a hermit crab climbing all over one, munching around him with no I'll effect on him. And it's not trying to retract either. Thoughts?

 

[Tahoe61]

I see sponges, possibly Pineapple sponges.

 

[reynaldoramon]

Do sponges withdraw into holes in the LR? They've all since gone back in.

 

[Tahoe61]

No they do not.

I guess someone else will have to chime in because all I see are sponges.

 

[Oscaror]

They don't retract into holes, but what you are seeing is them closing their mouths. They're pineapple sponges.

 

[reynaldoramon]

Thanks for the input. So weird how they just appear. They're benign right?

 

[Tahoe61]

Yes completely harmless filter feeders, their population will grow for several months and then die back as the tank ages.