Spiky thing in soft marine / brackish shale

[cngodles]

Here is an odd-ball I found yesterday. Recently I found a new marine / brackish layer of dark gray shale. My first discovery was two root pieces, which I'll showcase at another time. I also found a tiny Glabrocingulum grayvillense (gastropod) there. This particular rock had a brachiopod on it, and I was getting a closer look. The matrix was soft enough to stab with my tweezers, so I was digging around the margins. This very tiny piece appeared that looked very interesting, and even more complex under the microscope.

 

It's very small. The further out photo shows it with a 1 cm scale.

 

I feel like this is a known marine animal shape, but It's not apparent to me.

 

You can see the opposite part of it on the top right of the following photo as well.

 

Edited November 19, 2021 by cngodles

[Fossildude19]

My first impression was goniatite, but not sure if that is a possibility in your area.        

 

[cngodles]

Goniatites? Yeah, they exist here. But I've only seen two:

 

https://fossil.15656.com/catalog/specimen/CG-0091

https://fossil.15656.com/catalog/specimen/CG-0167

 

I don't know what they look like on this small of a scale though.

[Uncle Siphuncle]

Partial bivalve

 

[ClearLake]

@cngodles I am with @Uncle Siphuncle and believe it to be part of a bivalve. Check out the ornamentation on Acanthopecten carboniferus. You can see it on page 2 at the link below:

https://www.dallaspaleo.org/resources/Documents/PGUPFT 2a Mollusca first half.pdf

 

 

[cngodles]

That looks correct! Thank you.

[cngodles]

Well, almost. I do notice that the spiked ends align with the next row of spikes in the illustration. These seem to occupy the interspacial region from the previous spike row.