Paleozoic Fossil ID help

[JackyFisher]

These are found among river stones that yield a lot of crinoid fragments and worm traces. Any idea would be appreciated as the leaf-shapes are funky!!

[minnbuckeye]

Cross section through brachiopods? 

 

From Earth Science Australia: 

http://earthsci.org/expeditions/fossil_shapes/images/56%20oval%20brachiopods%20fossils.jpg

Edited July 25, 2021 by minnbuckeye

[JackyFisher]

thats a great idea thanks!

However should the shell leave some structure like the photo you quoted? It looks like this one have homogenous content and despite being cross-sections from various directions, they all have the same shape

 

[minnbuckeye]

 

 

Here is a geodized brachiopod in cross section that mimics what I see in your example except yours are infilled completely. A thin outer layer (the shell) appears to me to be there in your photo as well as in this example. Maybe it doesn't exist when examined in hand and if so, there goes my theory!!!!

 

From u/AsiaAfrica22

Edited July 26, 2021 by minnbuckeye

[TqB]

I think brachiopods too - there's enough variation in the shape, and the shell is visible around the calcite infill.

Like these Mississippian ones I find, photographed wet. (A couple, especially one at the top, have the spiral brachidium visible - only some types of brachiopod have these.).

 

[FossilDAWG]

I agree with brachiopod cross-sections.  The last photo shows trace fossils, some sort of a burrow or feeding trace (i.e. "worm traces").

 

Don