While searching an exposure of the Keyser formation near Mt. Union, PA I found some odd rounded objects.
I think they may be Cystoids but when I found them they had no discernible markings. Thinking them to be chert nodules I soaked them overnight in some vinegar and that is why they look a little etched. It wasn't until I got a closer look at the etched pieces that I noticed what looked like a pattern of plates. You can see what I am talking about in the specimen below.
As you can tell from the pictures above it seems to have a diamond shaped cross section so maybe that represents a top and bottom. I do not see any clear evidence of a stem or arms though. At this point it looks like the pattern may be an internal mold of a Cystoid or Crinoid but I doubt I'll ever be able to ID it since there it little to go on.
The Keyser formation is upper Silurian to lower Devonian in age (Pridolian to Lochkovian stage).
Interesting preservation Dave,
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