A feature lost on me, but they look like ammonites, which I love and are numerous around here. Here's one we found on the beach at Lyme Regis recently, It's a meter (3 feet) across!
They're such a fundamental part of part of nature and mathematics and their appeal is as ancient as the sun.
It's no surprise, then, that jewellers return to this motif nor that it's so popular. I certainly can't resist .
So, I'm still practicing .