Fossilized cretaceous sea worm?

[Creek - Don]

Found small sea urchin next to the ammonite in Lake Texoma Duck creek formation over the weekend. While I was cleaning the sea urchin, I noticed something that caught my eyes.  It appears to be a small worm that lived in Cretaceous sea, gotten attached to the sea urchin and fossilized at the same time.  Anybody familiar with sea worms like this?  

[Tidgy's Dad]

Indeed. It would seem to be a very nice specimen of Serpula sp. or at least a serpulid worm of some ilk.  

[JohnJ]

I agree with Adam.  These can be fairly common on Texas Lower Cretaceous, irregular urchins.

[grandpa]

I three agree.

[Creek - Don]

Thanks. Usually sea worms don't fossilize due to their soft body, but this one did.  Also found several bivalves with both sides attached,  which is rare. This site has some excellent fossilization sediments that I have not found anywhere so far.  

[Ruger9a]

Beautiful specimen, near perfect.  Really awesome! 

[Tidgy's Dad]

16 minutes ago, Creek - Don said:

Thanks. Usually sea worms don't fossilize due to their soft body, but this one did.  Also found several bivalves with both sides attached,  which is rare. This site has some excellent fossilization sediments that I have not found anywhere so far.  

The worm itself didn't fossilize, this is a calcareous tube that the creature builds for defence. If threatened the worm can retreat into it's tube and close an operculum (door) to seal itself inside. 

[facehugger]

I have a few heart urchins from Duck Creek formation with the same worms (tubes). Thanks for all the info, guys!

[JohnJ]

Like Adam said, these are not fossilized worms: they are the tubes they lived in.