ID on Fossil Sea Shell?

[Dug]

Hi;

I tried signing up for a group called Fossil Seashells on Facebook to get an ID on this item I found but apparently it is a poorly managed group as I am still waiting to get in days later after my request.

As a long shot I thought I would post here to see if someone could ID this.

I happened to be along side an asphalt road near a section that was eroding in the South Carolina Lowcountry. A flash of Orange caught my eye in the road's crumbled limestone underlayer that had tumbled loose. I assume it to be some sort of bi-valve that is missing it's 2nd half as seen by the hinge point that is seen in bi-valves. No clue how old this could be as I have no knowledge where the matrix was quarried for the construction of the road. I assume the matrix to be Limestone but could be wrong. The matrix is extremely hard and difficult to chip loose.

I also seek recommendations on far I should clean it to try to reveal more of the shell.

 

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[Planko]

Just a guess due to quite a bit still in the matrix...Here is my guess:

Cretaceous - EXOGYRA COSTATA SAY from the eastern Gulf region and the Carolinas.

 

[Dug]

Planto: After viewing your suggestion on the net I do believe you have nailed the ID, thanks.

Any tips on removing the matrix? A dremel tool with cutting discs and diamond bits is going to be a slow messy process.

 

[Planko]

Well, there are easier ways like vinegar and/or peroxide mixtures. It will ruin the color on that piece though. I would not recommended anything but hours of work.

 

[Dug]

After working on it with a Dremel and also an engraver I have removed the upper matrix to reveal that part of the shell is gone. Oh well. Making ear rings with it next.