ID please!

[Nikkoli110]

Saw this today when the lights came on. I was guessing it was some kind of worm, it was about 1 1/2 inches long, but it swam really fast in circles, and then went hiding in the powerhead. I tried really quick to take a pic but it went hiding into the powerhead. It was the first time I have seen anything like it in my tank, and kind of got worried. I tried searching on Reefcentral and only found one thing that sort of looks like it:
http://reefcentral.com/gallery/showphoto.php?photo=91289&papass=&sort=1&thecat=562
But not sure if thats it or not, but it just kinda creeped me out how large it was and how fast it swam around.

 

[Moe_K]

the linked picture looks like a lancet, i think?

 

[smcnally]

I had a lancet in my tank. If you disturb it, it will zip around the tank like that. It will probably die soon. They don't last long in tanks from what I'm told.