ID hitchhiker - big feather duster?

[dendro982]

Can you ID this:

small turbo snail for a comparison. Something like the giant Hawaiian feather duster, only attached to the rock. I had never see the crown - all this was hidden between rocks.
Thanks.

 

[LeslieH]

That could be the tube or a feather duster in the polychaete family Serpulidae or it might be a vermetid mollusc. If you never see a crown but there's mucus strings coming out of the opening it's a vermetid mollusc.

 

[dendro982]

There are few ~ 1/32" (2mm) thin lines showing, and something solid in the center - but it's far between the rock to say for sure. And sharpnosed puffer in the tank could eat insides, after they were exposed during aquascaping.
Thank you.

 

[LeslieH]

It does sound like a vermetid. While most of the vermetids that show up in tanks are small & multiply rapidly there are some large species as well.

 

[dendro982]

Thank you! Without your help I could spend months on the web, trying ti ID this.