What is this?? *PICS*
 

First...I have tried taking pictures of it but the tentacles are so thin that they dont show up.
SOOOO a description of what I can see is the best I can do. I have seen 6-8 tenticles that seem to be able to reach about 14" in length, they are about as wide as a thread and feel all over with the tip. they are brownish in colour, and come out during the day. I have some spaghetti worms in another tank and they are not nearly as big as this thing I am describing. I assume it came in on the live rock, it hides behind/inside one of the rocks. I used a grabbing device to try and pull it out and it broke off the tenticle I was touching and pulled in. I have tried to no avail to see its body with a light. Doesn't seem to affect any coral that it touches and no livestock has dissapeared...yet.
Sorry but this is all I have at the moment.
IF I can get any type of pic that shows it I will post it up right away.

probably a brittle star. Are the tentacles sort of greyish and possibly striped/mottled with black? Likely they're tiny brittle stars.

here is pic, remember this pic shows it as pretty big when in actual fact the disc is about the size of a pinhead (maybe a bit bigger) and the arms are about the diameter of a pin. They're pretty tiny critters.

And they're good :biggrin:

http://www.xtalworld.com/Aquarium/brittlestar.jpg

No I have a few of them in my tank and I would know if it was one of them. The arms?/tenticles?/legs? are brown and look smooth.
the brittle stars that I have are close to what your pic shows and imagine the legs as thin as a star but as long as your forarm. and they dont seem to taper at all.

I know without a picture it will be tough to figure out but they are so thin they dont show up on the sand. it seems to only "feel" the sand

OK so here are a couple pics.
if you look you can see the thin strands from it.
they can reach at least 14"!!!!!
http://img.photobucket.com/albums/v2...s/PICT1770.jpg
http://img.photobucket.com/albums/v2...s/PICT1769.jpg

I have the exact same things in my tank but I cant help you on identifying them. Mine just seem to come out of nowhere (the face of a live rock) I thought it was a thread so I pulled it off(came off after a bit of tugging) but 4 days later it was back.

I still say spaghetti worms, there are different types and the tentacles can reach 4ft long. There are some pics half way down this page

http://www.marinelifephotography.com...s/annelida.htm

I'll agree I have some with like foot long ones they will catch some food on just roll it in

spaghetti worms, good scavenger.

would those tentacle thingies bother corals though?

Mat, I have these "threads" in my tank as well. Mine are kind of a dark yellow color and come out from the rocks.

It's like a loose spool of thread that's just in your tank for whatever reason, right?