Can someone identify this for me? Petrified Acorn?

[GreddyM3]

Wondering if anyone could identify this for me from the pictures. A unique feature, is the diamond like crystals on one part that I will try my best to get good pictures of. Thanks for your help!

 

[TheCannonballGuy]

Still sick, so just one post. Fifty years ago, I was (among other things) a rock-hound and fossil hunter. To me, your find looks like a broken-off wide end of a fossil, from the Ordovician Period of geologic history and now extinct, specifically a "Solitary Rugose Coral" a.k.a Tetracorallia, a.k.a. "horn-coral."

See the photo on the right, and the info, at the Wikipedia entry for Tetracorallia, here:
https://en.wikipedia.org/wiki/Rugosa

 

[cactusrat]

I think Cannonballguy nailed it. I was thinking something like that, but didn't have any words to sprout out. My rock hounding didn't stick inside my head as well.

 

[GreddyM3]

Very interesting. Thank you very much for your responses. Greatly appreciated.