What is this and is it going to try to take over my tank?

[keonia]

Help! i found this growing - and getting larger
then I went in to try to scoop it up, it recessed. I tried to scoop out the area of sand around it but it was too quick - and LR was in the way!
I also see a bunch of hair like things that seem to be coming out from under the rock.
Does anyone know what this could be?

 

[drew2005]

Spaghetti worm? Check out the hitchiker thread up top and go to reef worms.

 

[airforceb2]

It doesn't look too big...most likely beneficial to your tank. Check the HH thread to be sure though.

 

[keonia]

Thanks for the replies!
I did check the hitchhicker post and it was nothing like what I have in my tank. I don't think its some kind of algae - thought it could have been hair algae but it moved and hid when I was near.
in the picture 2 & 3, they look like one fat thingy but at the end, it's stringly and it looks like a bunch of it all bunched together -- I'm wondering what in the world happened to it when I tried to scoop it up?
I looked up a picture of a spagetti worm... it doesnt look like that.
anyone? :help:

 

[tennisace]

can we get a clearer picture a little closer up, we can't see any details of the worm to identify it? Ty

 

[keonia]

Thanks Tennisace for looking.
I'm gonna try to find it again, I tried to scoop him out and it vanished!! but the blurry part looks like a string of those hairy things and it was bunched all together. It kept moving so it turned out blurry! :scared:
I am going to try to life that rock in the 1st picture (using safe gloves or something). Those hairy things hid under the rock kept moving and as it sense me (a predator) it went underneath.