What is this growing on my outlet?

[bandrews]

There is one on the bottom and one on the end. They have appeared in the last couple weeks and are growing quickly. Looks like a cacoon with a tube worm head on the end

 

[sasscuba]

sponge

 

[Pea-brain]

Yep, harmless pinneapple sponge. Won't hurt a thing. Probably benificial. They multiply fast but then they start dissappearing as the tank matures.

Dan