Crinoid blossom? Found in East-Central Illinois

[discarded2]

I found this about 20 years ago. I was once told it was a fossilized crinoid blossom. I can see some similarities but nothing I've seen is close enough for me to be sure. Thanks in advance.

[discarded2]

One more picture. It has quartz crystals on the inside.

[Fossildude19]

Where was this found?

Looks a bit big for a crinoid calyx.

I think you may have some rugose corals there.

Regards,

[discarded2]

Edgar county, Illinois. I found it while walking in a field. Only a small part of it was exposed. I thought it was a rotten tomato so, naturally, I kicked it. It wasn't a rotten tomato.

[discarded2]

Thank you for your speedy input.

[Fossildude19]

Ouch!

No problem.

I am not seeing the plates you would expect to see on a crinoid calyx.

I suppose it could be geodized, which can alter the shape of things.

Let's wait to see what some others have to say.

It is cool, whatever it is - I would have kept it.

Regards,

[tmaier]

I agree with a colony of five rugose corals.

[FossilDAWG]

Nothing about the specimen indicates a crinoid or other echinoderm, except the five-fold symmetry. As Tim said, there is no indication of any of the plate structure one would expect to see. Instead the surface is covered with wrinkles which are highly similar to growth lines of rugose corals. I agree the specimen is most likely a colony of rugose corals.

Don

[Harry Pristis]

This appears to be a Mississippian geode which may have developed from some organic focus with pentameric symmetry (like a crinoid calyx). Other diagnostic features are obliterated by the deposit of silica. You might label it a "pseudomorph after crinoid calyx," and who could argue with that.

[Oxytropidoceras]

I would agree with the identification that it is a Mississippian geode and

a pseudomorph after a part of a crinoid. It is a silica pseudomorph of an

anhydrite pseudomorph of part of a crinoid that has pentameric symmetry.

The initial replacement of a crinoid fossil by anhydrite often "explodes"

the shape of the original fossil into an object barely recognizable because

of the increased volume of the replacing anhydrite.

Go see:

Chowns, T. M., and Elkins, J. E. (1974), The origin of quartz geodes and

cauliflower cherts through the silicification of anhydrite nodules, Journal

of Sedimentary Petrology. vol. 44, no. 3, pp. 885-903.

Maliva, R. C. (1987), Quartz geodes: Early diagenetic silicified anhydrite

nodules related to dolomitization, Journal of Sedimentary Geology.

vol. 57, pp.1054-1059.

Milliken, K. L. (1979), The silicified evaporite syndrome: Two aspects of

silicification history of former evaporite nodules from southern Kentucky

and northern Tennessee: Journal of Sedimentary Petrology. vol. 49,

pp. 245-256.

Chowns and Elkins (1974) discusses and illustrates what happens to

crinoids when they were replaced by anhydrite.

Also, look at:

"The Gee!-Ode" What a weird hide, With such joy inside!

by Bob Jarrett, The Georgia Mineral Society, Inc.

http://www.gamineral.org/writings/geodes-jarrett.html

Yours,

Paul H.

Edited July 23, 2016 by Oxytropidoceras

[discarded2]

Thank you all for your input!

[doushantuo]

or:

Henchiri(2006)

https://www.researchgate.net/publication/229724139_Silicification_of_sulphate_evaporites_and_their_carbonate_replacements_in_Eocene_marine_sediments_Tunisia_Two_diagenetic_trends

or:

https://www.researchgate.net/publication/230364535_Silicification_and_dolomitization_of_anhydrite_nodules_in_argillaceous_terrestrial_deposits_An_example_of_meteoric-dominated_diagenesis_from_the_Triassic_of_central_Spain

Edited July 23, 2016 by doushantuo

[abyssunder]

It is a geodized crinoid calyx , I agree. Nice find ! Similar one is in this older TFF post : http://www.thefossilforum.com/index.php?/topic/22442-geodized-fossil/

[discarded2]

That's what it is for sure! Thanks so much!

[FossilDAWG]

I now agree, especially after reading some of the links Oxytropidoceras gave, that the specimen may well have originally been a crinoid calyx, with the plate structure now totally erased by anhydrate growth.

Don