Radulopecten bivalve but unknown passenger

[DE&i]

I have this Bathonian bivalve from the Upper Cornbrash, UK which I think is Radulopecten vagans.

 

 

 

Any suggestions as to the passenger it is carrying. 

 

[TqB]

A serpulid of some sort I believe. I don't know of a specific Cornbrash one but Tetraserpula is similar, for example.

[DE&i]

Thank you @TqB good call with a serpulid look to it. Perhaps someone on TFF might have some reference material.