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Mississippian spiky ball, apparently non-crinoidal


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My fossil hunting friend came across this object in a creek in eastern Missouri. At first glance this ~1 cm diameter ball with stout spikes would seem to be some sort of camerate crinoid, but the spikes cover the entire surface, with no apparent place to put arms, column, mouth, or anus. (Side note: That must be the crinoid folksong community's version of "Head, Shoulders, Knees, and Toes.")  From there my fallback would be coral, or perhaps sponge, but the complete coverage around the whole sphere (see attached video) has me a bit baffled.

 

The creek flows through mostly Meramecian (Visean) Mississippian bedrock, in particular the Salem Limestone. There is abundant chert, with common silicified fossils, which is what I believe this to be, though I have not examined it myself. Perhaps this is the internal mold of something? The chert bits I have seen from this creek, and from this region in general, are by and large not internal molds, but rather proper replacement fossils. I guess this oddity just has me reaching.

 

Any thoughts with regard to identification would be most appreciated. 

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DPS Ammonite

By Jove, we have found probably the same unidentified fossils. What are the associated fossils in the area? Any sponges? Are there any Pennsylvanian formations in the area, names?

 

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An early version of Willy Wonka's Gobstopper?

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DPS Ammonite

Maybe, Gobstoppers are "Everlasting". Maybe "Gobstopper" should be part of its name if it is a new species.

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It does look like the coral pachyphyllum woodmani as identified by @BobWill In earlier thread link provided.

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8 hours ago, westcoast said:

It does look like the coral pachyphyllum woodmani as identified by @BobWill In earlier thread link provided.

Actually, like DPS Ammonite I think,  I was never totally convinced about that ID or for that matter  another suggestion from the same thread linked above, the algae Lithophylum. Somebody needs to do some definitive work on these so we can be sure.

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Thanks all for your responses thus far! Alga does make a lot of sense for a ball that rolls around freely, if that's indeed what this represents. But I'm still not even 70% convinced one way or the other....

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Going back to @DPS Ammonite's linked post: these look like silica steinkerns of a favositid coral of some sort, with prismatic corallites. The connecting processes would be mural pores.

 

Near spherical is unusual but not unknown, possibly encrusting something.

 

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Xiphactinus

Any chance you can get closer photos with better lighting? Outside maybe?

 

Looking at your second photo, it appears the spikes on the left of your photo are shorter than the ones on the right. It also looks like the ones on the right seem to angle a bit to the top. Sure has a "crinoidy" look to me.

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  • 5 months later...

I just came across this thread again. The lithistid demosponge Haplistion has very similar geometry (also suggested in DPS Ammonite's post linked in the second comment here).

 

This monograph specimen of H. vermiculatum Carter is from the Mississippian of Scotland. (If yours does indeed show spicular rods, they may be overgrown with silica.)

About 1cm across.

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Thank you Tarquin! I'l referred this and the other hypotheses to the finder of the fossil for her approval. Hopefully one makes total sense, but we'll see...

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