The girl and the shell both look so fragile as they are drawn in a soft way by enhancing the darker areas. I love the outline on the drawing and I think it shows that the character works good on its own, without any background.
Ammonites went extinct with Dinosaurs 65 million years ago. Ammonites survived until the end of the Cretaceous period in a sea that covered what is now Alberta. Canada and Montana, USA. These ammonites were transformed into the rare gem known as Ammolite.