Hitchhiker ID - Thin Micro Tentacle/Worm

[DreadCapn]

I have a tiny, smooth tentacle/worm that occasionally extends out of a little bump of a rock or shell that is attached to a coral plug. It is approximately 1" in length fully extended, and about as thin as a mechanical pencil lead. I assume that it is sessile, as it hasn't moved in the 3 weeks I've had the coral.

It occasionally comes out and waves around (actively and a little questing, not just movement in the current). It reminds me of the siphon on a nassarius in its movements.

I did dip the coral (it's a mushroom) in Revive, but this and a tiny feather duster of similar size apparently survived the dip.

I assume it's harmless - any other opinions?

I don't know that pictures would do any good in this case - I will take some next time I move the frag plug

 

[Sugar Magnolia]

Probably a vermetid snail.

 

[DreadCapn]

Just a pre-update - I am planning on pulling the frag out tonight and grabbing pictures.

I don't think it is a vermetid snail (could be very wrong!). I've also discovered that it's NOT sessile after it disappeared for several days, and then reappeared this morning (I think it crawled back under the mushroom, it's right back where it originally was today).

For a better description pending the picture, it almost looks like a tiny sculpture of a turtle made out of 6 grains of coarse white sand, with the tentacle coming out of the 'head', basically like this:

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