Strange animals growing in sump

Maybe someone will know what they are? They're growing inside the skimmer too. Any info would be good. Thanks

 

looks like a tube worm. maybe a sponge. either way there fine/even good to have.

 

i have no idea what it is, but im watching this. i have some of those on my rock in my DT.

 

I have several critters in my sump as well and am torn between cleaning it out completely (worried about detrimental effects) or just leaving them be seeing as how all seems well.

 

It's a sponge

I couldn't tell you which kind but they like to grow in dark places. they are harmless filter feeders.
I have the same type growing behind my overflow box

 

Good to hear it's nothing to worry about. Thanks

 

Looks like a tunicate to me which like a sponge is a harmless filter feeder, but if it grows in the sump, leave it be. Its probabaly the best place for it as this would be the most nutrient rich part of your tank.

 

+1 on Tunicate, they are a sign that the tank is doing really good.