Should this guy concern me?
 

I was just peeking into my tank last night when I saw what I thought was a polyp that I didn't recognize.

When I got a little closer, it pulled back some but didn't close. After a closer inspection and a few fuzzy pictures I think it might be a worm...and not a good kind of worm.

Here's a picture...can anyone confirm what this might be... Note that though it's not sticking out far right now...it was out about another inch when I first saw it. It's a little thicker than a pencil by my estimation.

http://i485.photobucket.com/albums/r...g?t=1231541252

http://i485.photobucket.com/albums/r...g?t=1231541579

Thanks for any suggestions.

Hard to tell, but looks like Aiptasia to me.

second that ^^

Nothing to be overly concerned about but you do want to kill it!

http://inlinethumb59.webshots.com/44...500x500Q85.jpg

+1

Haha...thanks but I'm pretty sure it's not aptaisia. I've had that tank running for over 2 years, haven't added anything in a long time and never had aptaisia in it. I also have another thank with aptaisia problems, so I'm used to dealing with them.

I am more afraid that it's one of these...Eunice worm

http://farm4.static.flickr.com/3211/...664cda.jpg?v=0

They seem to share the same mouth...multiple tentacles at it's entrance.

If it is a eunicid worm, then it could be good or bad. I had one for a long time that was vegetarian. I probably have several hundred in my tank right now, but they are all small and harmless.

Okay, so this is an old thread but that "polyp" or whatever it is has multiplied and switched the direction that it was sitting.
It only comes out at night or in the dark. It's also multiplied...though you can't see it well here, there are three of them now all looking in different directions. If you look down and left beside the larger mushroom, you can see one of the babies though it's color is muted.

Here is the pic:
http://i485.photobucket.com/albums/r...g?t=1311711060

Coloration is a brownish with fairly bright green blotches in the center. It is almost an inch across now.

Again, never had aptaisia in this tank...haven't introduced anything in a long time.

It could just be a polyp but I've not heard of many that only come out in the dark and close all day (even under the overhang that protects it from light). I have had a few small fishes disappear and it seems that when they do, this doesn't come out for a few days around that time. Otherwise it's out every night.

Any thoughts?

my money is on mojano.
you could easily have one (or aiptasia) and never know it for years.

Looks more like a pseudocorynactis, but it might just be the pic.

Hope that its not like this one if it is.

http://www.oregonreef.com/sub_worm.htm