500 million year old what?

[Blondefly]

Hello!

I am splitting some shale (Utah) and found this in the split, in a shale piece about 3-4” thick. Trilobites are on both sides and I’m sure embedded. This large egg shaped piece is about 1/4-1/3” thick. A black piece in the area as well. Any idea? Thx (ps the background colored shake  is from NV, different source. I just put these there to take the picture).  Thoughts? Thank you

Edited November 21, 2024 by Blondefly

[Fossildude19]

Looks like a nodule or concretion.

Not sure what the black dot in the center is, though.

[rocket]

sorry, no fossil, a sedimentstructure

[minnbuckeye]

At least there are trilobite pieces in the matrix!

[debivort]

from a friend who is expert in the Wheeler: the "egg shaped piece" is just a concretion, so a slightly more consolidated bit of shale that forms somewhat distinct from the broader matrix. There is nothign fossiliferous there. The black bit might possible be a shell of something, but it is hard to tell. Maybe a brachiopod or similar.

[Rockwood]

Is the lighter colored material a thin but quite distinct layer? There is a fossil alga known to be found there. My specimens from the U-Dig quarry are flat and paper thin but I remember reading that they are thought to be globular shaped in life. 

[debivort]

1 minute ago, Rockwood said:

fossil alga

if you mean Morania, it is preserved as small patches of carbonaceous film. Quite different from this (which I agree looks like a concretion).

[Rockwood]

14 minutes ago, debivort said:

if you mean Morania, it is preserved as small patches of carbonaceous film. Quite different from this (which I agree looks like a concretion).

Yes, that looks like it. I have to admit that this post doesn't look just the same though. 

[Moth.11]

No fossil 

[Blondefly]

Yes, there’s trilobites all throughout. I didn’t want to do anything with them until I figured this out first.  I have a wide variety of thick/thin/types of full and partial trilobites in this dark shale. Never seen this blob before. 

Edited November 21, 2024 by Blondefly

[Moth.11]

Nice trilobite pygidium next to this.