weird white thing on my zoa frag

[Hoopster81]

I'm a beginner so this might be something totally harmless/normal, but anyways..

I removed this zoa frag yesterday to give it a H2O2 dip because it has sprouted some GHA. Today I noticed a small, white, egg-shaped object on the bottom of the frag. I believe that before the dip, this side of the frag was faced away from the glass, so I have no idea how long it has been there. I just looked at it again when the tank lights were off, and I noticed it has a longish (1/2") filament extending from it now.

Got a couple low quality pics attached..

[Hoopster81]

Here are a couple pictures in the light. It is to the bottom-left of the center polyp, above the disc. The long filament is now retracted.

[mcgyvr]

Can't see anything in those pics.. out of focus,etc..
Check here to see if you can find it..
http://www.lionfishlair.com/hitchhikers-guide/

First thing I think of when you say a filament sticking out is a Spionid Tube Worm