ID help please!

[tobysmurf]

I took my newest torch coral out of QT today and put it in my display tank. When I pulled it from QT I noticed the "shell" and hole at the top of the one head. I ignored it, as I didn't see anything in it. Tonight I came home after the tank was lights out, and noticed something moving rapidly. Please see the attached pic. Whatever it is, it moves fast! The small spikes come out, rotate around fairly rapidly, then pull back in every 15-20 seconds like this critter is eating. Any idea what it is? If you do, do I need to get it out of my torch?

http://i41.photobucket.com/albums/e273/tobysmurf/Reef%20Tank/Small_Backpacker_zps3653bfd7.jpg

[mrhasan]

Barnacle :D I have like 3/4 in my tank on my hammer coral. Harmless filter feeders.

Just for reference, this is what barnacles look like:

http://shiftingbaselines.org/blog/Barnacle.jpg

[Din Gior]

Looks like feather duster worm.

[tobysmurf]

I have tons of feather dusters in this tank (7-8 "pest" ones and two that I bought). The little spikes don't really look the feathers of the feather duster - they look almost like claws. Also none of my feather dusters move like this (correct me if yours do). My feather dusters tend to open slowly, and stay open unless disturbed for long periods of time. This thing is constantly going in and out, and it rotates around a lot. It's kind of creepy! Now that I know to google for barnacles, I see ones that look just like it in youtube. This coral also came with a yellow sea cucumber on it, so I'm counting this barnacle as another bit of bonus biodiversity! This is the sort of thing that keeps owning marine critters interesting!

[jagermaier]

It is 100% a barnacle...