Mysterious black long tentacles

[SmokeyTheReefer]

I just got this acro yesterday, and we noticed these long black tentacles coming out of what kinda looks like a barnacle on the base of the acro. It flows with the current. We thought it was a tiny urchin or something. Just making sure it's not a problem. Hopefully the picture can be good enough to identify. TIA!

 

[littlefoxx]

 

[SmokeyTheReefer]

Hey, at least I can identify that.

 

[littlefoxx]

Hey, at least I can identify that.

sorry I couldnt resist! Ive got no clue what that is but thats what came to mind @ISpeakForTheSeas ?

 

[ISpeakForTheSeas]

sorry I couldnt resist! Ive got no clue what that is but thats what came to mind @ISpeakForTheSeas ?

I am super late on this, but any chance of white light pics/video, OP? If not, my first thoughts would be either a barnacle or a cage worm (family Flabelligeridae; not all species look similar to this, but some - like those of the Daylithos genus - do) from what I can see of the "tentacles" in the video.

There's not much info that I can find on cage worm diets, but I wouldn't expect them to be very harmful if harmful at all; barnacles are generally harmless with some exception for coral-boring barnacles (where the barnacle is literally growing inside the coral; this causes deformed growth, and if the coral is small enough/the barnacle big enough, sometimes the death of the coral colony).