Horrifying tentacles reaching

[ratsark]

I discovered a fairly long tentacle reaching out of a zoanthid colony earlier today, apparently sifting through the substrate. I've never seen such active tentacles before! It pulled back and reached out to different places ever couple of minutes, and had small tentacles that were constantly active.

 

See the video here:

 

So far my best guess is hydroid, but I'm not sure they reach so actively. It could also be one of the many phyla of worms, though I have no idea which one.

 

Thanks in advance for your help!

 

Edit: put up a better-quality video

[heywooood]

Hard to tell from the video but it looks like a peanut worm. I have a couple that stretch out like that every now and then, disappear when you shine a flashlight on them.

[Mariaface]

Awww, horrifying? It's adorable! And yes, it's a peanut worm. Beneficial hitchhiker that'll eat detritus and leftover foodstuffs. I've got a few in my tank, I remember being really confused at those feeding tentacles (it's like a duster!) when I first saw them.