Hitch hiker ID

[AndyL]

Posting this here... I can't seem to find anything like it among the normal hitch hikers.

My camera doesn't do macros well apparently - Did the best I could. should give you the basic idea anyway.

Its embedded in the rock roughly 3/8" diameter, has a split shell, concave on the visible side. Several green feeder tentacles. Mouth is black and white striped (reminiscent of a clam). It keeps 'puking' out a long spiderweb, then eating it.




Thinking it could be a Vermetid Gastropod but most of those are shaped like a tube worm - this is more clam/barnacle like...

Idears?

Andy