A worm or a slug ?

Dear fellow worm lovers

Any idea about this ? It is a top view of a tube (like the ones fan worms live make). Mediterranean, about 1,5 cm diameter.

Looks to be the operculum of said worm (looks like a serpulid) which is retracted into its tube. Can't tell which one it is, though. Perhaps Leslie can help.

Cheers,

Marli

Not quite an operculum and not quite a worm either. This is a vermetid worm snail, a group that lost the ability to coil like the rest of the gastropods. Instead of using an operculum to block the opening of their tubes the snails use the foot. I don't know the european worms very well, let alone the worm snails - but your pic does match one of Serpulorbis arenaria on this page of Italian molluscs http://www.sim-online.it/Risorse/moll_vivi...da%20marini.htm

Thanks a lot Marli and Leslie !

That must be the one! Interesting, a snail going worm. The popular name is "Giant worm-shell" or "Vermet géant" in french.

I learned that this worm-snails' shell is of an irregular right-turning form with only the first tours (20mm) joint.

As Leslie pointed out, the brown-red-golden part of the body that is visible is the foot, which lost it's original functionality of movement and is used now to block the opening of the shell.

On the picture you actually see part of the tentacles.

http://www.flickr.com/photos/svenalgerie/672304574/

Sven.