Fossil Geode

[Bootsuki]

Found at a junk store in Graves County, Kentucky. Unfortunately the owner didn't remember what estate sale he found it at. I bought it as a simple geode but after cleaning it up I think it may be a geodized crinoid calyx. Its extremely heavy, sorry, no bananas for scale. Thoughts?

Edited April 17 by Bootsuki
Added note about being heavy.

[Fossildude19]

At over 8 inches across (best guess-timate) that would be a HUGE crinoid calyx.  

I have serious doubts. 

[Isotelus2883]

Because of the quartz crystals, the geodes can end up many times larger than the actual calyx, which is not uncommon for these.

[Harry Pristis]

1 hour ago, Isotelus2883 said:

Because of the quartz crystals, the geodes can end up many times larger than the actual calyx, which is not uncommon for these.

I think these geodes continue to grow in size as long as depositional conditions are right.  That is, as long as SiO2 continues to be available and the limey matrix remains soft.  Quartz crystals are incidental, forming in any void in the geode.

 

 

[Fossildude19]

Besides the large size (No bananas for scale, but any ruler or tape measure???)  I do not see the symmetry needed for this to be readily identified as a crinoid calyx. 

I'd be happy to be proven wrong. Just not seeing it, personally.

 

@Bootsuki - any chance of actual measurements being posted?

 

 

[FossilNerd]

From my experience and research, size of the resulting geode can be much larger than the beginning calyx and often “swell” when growing. I can show multiple examples when I get home from work if it would help.
 

That being said, I still don’t think this is a geodized calyx, or at least not recognizable as such now. You would typically still see some semblance of a calyx, symmetry, shape, or other evidence of what the geode once was. I see none of that. This looks like a standard run of the mill geode to me.