What are these Caterpillar type critters?

[Mal]

Does anyone know what this is? I have many greyish/green flat caterpillar/worm creatures in my live rock. They come out of the holes in the rock at night when the light is out. Sometimes I see one in the day, but at night they are all over. They are from 1 to 3 inches long. Do you have any idea what they are and if they are good for the tank?

Thanks for the help

Mal

 

[wade1]

It might be much better and more responsive if you posted this in the hitchiker forum:

http://www.reefs.org/phpBB2/viewforum.php?f=22

I can't really hazard a guess based on your description though, can you provide more details? width of the flat body? segmental? mouth apparatus? pictures? detritus left behind or feeding habits?

Wade

 

[Mal]

I finally got a photo of it? What is this?