What are these white tube like invaders?!

[Jbr0nc0]

I think they may be some sort of sponge/filter feeder but the other part of me thinks they were sent from outer space to kill everything in my tank

 

[cloak]

Pineapple sponges. (good)

 

[AlyciaMarie Verified Admin]

I also have some pineapple sponges in my tank. It's so funny to see the snails zooming around the tank with these on their shells.