ID Assistance Please

[Paleo_Adventure]

Hello, I purchased two of these years ago. I was told it was coprolite. Since then, I have learned allot and have doubts this is actually coprolite. So, what is it?

 

As seen in the pictures, they look like a ball was shoved into a large tight donut hole. For reference, the tile is 12 in square. Both are very symmetrical. It appears to have rust color but no other indication this is an iron concretion. The outer "shell" to me looks like it cracked under pressure, but the center ball did not. Although curious to the possibility of having contents, I do not want to do a destructive investigation.

 

Your input is very much appreciated. I share my finds and information with teachers and students. So, I want to be as accurate as possible.

 

Thank you,

Paleo Adventure

[Fossildude19]

Not sure of the mineral makeup of the thing, but definitely some sort of Concretion.

Could be some form of ironstone, or siderite.

[Paleo_Adventure]

Thank you, the concretions I have seen do not have this symmetry and the "shell" at the edges indicate to me that this was inflated more and crushed from top and bottom. Whatever is in the center creating the bulge on top and bottom could be harder than the surrounding material. To have two of them of different sizes and get the same shape tells me they both went through the same process. Thanks again for your input.

[Randyw]

I'm with fossildude on this one. Flat concretions with bulges are not uncommon....

[Fossildude19]

6 hours ago, Paleo_Adventure said:

Thank you, the concretions I have seen do not have this symmetry and the "shell" at the edges indicate to me that this was inflated more and crushed from top and bottom. Whatever is in the center creating the bulge on top and bottom could be harder than the surrounding material. To have two of them of different sizes and get the same shape tells me they both went through the same process. Thanks again for your input.

 

And without breaking it open, or preparing the concretion somehow, you'll never know what the cause of this is.
As stated, these are not uncommon features in concretions. 

[Mark Kmiecik]

8 hours ago, Paleo_Adventure said:

To have two of them of different sizes and get the same shape tells me they both went through the same process.

 

That's a very common occurence. Google Mazon Creek fossils. The concretions formed around plants and fauna. Hundreds of thousands of leaves of the same shape and size, and therefore extremely similar concretions. Your conretions may have also formed around organisms.