Turtle, maybe? Some kind of shell?

[GalInBritches]

Whatever they are, there's a LOT more where they came from - and more sizes and shapes!

 

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[Jason in Enid]

No , not turtle shell. Could be tree bark.

 

[MrBlueSkyNM]

I found something similar to that big piece a few years back. Never could figure out what it was. Good luck!