Very very old, and so inspiring!
Very old indeed, 68 million years!
It is an Ammonite (Sphenodiscus lenticularis) from USA, South Dakota, Cretaceous Period.
Isn’t this a beautiful pattern? Seeing this I just have to make a photo. I’d like to use it for an embroidery.
I saw this at the Ruhrmuseum, Zollverein in Essen, Germany.