Calyx?

[Jan Lester]

Unfortunately I don’t have any provenance for this rock. I bought it years ago screwed to a piece of driftwood for my fish tank. When the driftwood had withered away to a twig, I was throwing it away, but noticed the fossil traces on the rock and kept it. Came across it a few weeks ago, and started messing with it. The fish store was local, and I would assume that this was created by a somewhat local person (in east TN), but I don’t know. The top of the “calyx” is translucent  from the underside. Not the softest limestone I’ve found…I can see signs of bryozoans and brachiopods, but it’s hard to expose them.

[Rockwood]

Is the fourth photo down the opposite side of what is shown in the first ones ?

[Jan Lester]

Yes, the “underside” of the rock. Sorry, I should have noted that. 

[Rockwood]

I can't really see any definite indications that this is a calyx, but it sure seems possible.

[Jan Lester]

Thanks! I actually was thinking coral head, before a grad student who saw a pic said many calyxes (sp?) were geodes. Also the proximity of crinoid pieces seems suggestive. I want the “lines” nearby to be a crinoid head, but my son says bryozoan. Either way it’s cool.