mini hard tube feather dusters

[purge43]

Ive been noticing alot of these little creatures. Some are almost an inch long with a feathery type display coming out of the top and there only about a 16th or 32nd of an inch in diameter Ive broken some off my rock and the material seems calcious, I can break it like a piece of glass. The little bugges are definately alive, because they retract when i get near them. Other then using up my nutrients/food and alk/cal/mag suppliments are this guys friends or foes?

 

[droberts]

i have alot of them in my tank a couple of them behind my live rock are at least 1/4 inch. i have left them alone in my tank because they are a filter feeder and help keep my water clean

 

[Dino]

Yep, they're completely harmless filter feeders. Other than occasionally grabbing the small particle out of the water if you have any fish (or invertebrates) with a taste for small worms they might snack on them. You'll likely see them come and go in waves.

 

[ERICinFL]

Yep, harmless. They're not going to suck that much of your Alk/Calc/Mag either, so they won't be a detriment to your corals.

 

[Reefski's]

and they spawn and provide coral food.