What kind of hitchhiker did I find?

[holy carp]

Guessing it's some kind of fan worm. There were 6 or 8 of these on a frag I got. Some dropped off in the bag, or while dipping. I don't think any made it into the display. I had picked up a number of frags at the Manhattan Reefs Frag Swap, so I'm not positive which these were on, since I was rinsing and dipping them together.

 

It seems to crawl relatively quickly around the cup it's in, and usually ends up near the surface. It's about 6 or 7 mm long.

 

[arwndsh]

Looks like a feather duster

[amphipod]

Just a sabellidae worm outside of the tube, quite a few species have that basic pattern and look. Rest assured that no matter what, there is absolutely no way these guys can harm your tanks livestock.