Small white rings on glass, rocks, and shells

[ron-salt-tank]

None know what these small white rings are? They are popping up all around my tank on rocks, glass, and crab/snail shells.

 

[Sniperhank]

They are either pods or small filter feeders. If they don't move then they are filter feeders, that name is escaping me. My tank is covered with them. Harmless guys.

 

[ron-salt-tank]

They don't move, the are crusty looking rings. Do the grow bigger or stay small?

 

[kdpuffer]

They are small feather dusters. They tend to stay small and they are good filter feeders to have.

 

[Schism]

Spirorbid worms. Sp? Harmless filter feeders. Usually you will see the population explode, but after some time they will cut back to more reasonable numbers and stop reproducing so rapidly.