Weird tube thing on my Dendros - danger?


New member
Every day this week I've woke up to find a 1/4 x 1+" tube sack thing on my dendro colony.


It's empty like a used cocoon, but the polyp it is on doesn't want to open. I scrape it off every day and every night it comes back!

Is something trying to eat my dendros?

Only other info is I recently had some kind of bristle worm hitch hike in. Seems there is a kind that will 'lick to death' gorgonians.

Egg sack or saliva sack?
Infestation of some kind? Dip it?