Worm ID

[doomus]

I have posted this question earlier with out a picture. I need some help to ID these and advice on if they are something I should be concerned about.

They only come out at night. They are light brown and live in holes in the live rock. They are smooth and round. They don't look at all like a bristle worm. No feet or tentacles. I don't know if they burrowed into the rock or are taking advantage of natural holes. I have seen 5 but there are probaly more.

They are nestled sparaticaly through a mushroom colony and don't look like they are harming anything. They appear to be reaching down and sifting through the sand or scavaging the surface of the live rock. They seem to be limited to one rock and I have never seen one outside of the rock. They vaguely resemble a peanut worm but from what I have read on them I'm not sure if that is what they are.

Does anyone know what these are and if I should be concerned?

Dennis

 

[NaH2O]

IMO, the one on the bottom looks like a peanut worm.

I'm not sure if you've seen this thread, but Beaker Bob has taken some of the best Peanut Worm photos ever: Peanut Worm Pics

Here are a few links: Peanut Worms, Introduction to Sipuncula: The Peanut Worms, Peanut Worm

 

[Boomer]

Look like peanuts to me also

 

[payge]

We have several of these in our tank as well...I reviewed the link with pics in it....I've never seen the "duster" end with tentacles come out tho...and by the "i wish I hadn't killed mine" comment they are a good thing?? or at least not a bad thing??

Thanks

 

[NaH2O]

They're a good thing....harmless detritus feeder. Here is another article: Reefkeeper's Guide to Invertebrate Zoology: Part 6: Phylum Sipuncula and Phylum Annelida