Ammonite - The Fibonacci Fossil

This is not a real ammonite. It is a model of the popular fossil which resides in my front garden. I am fascinated by the spiral shell that forms a Golden Circle using a Fibonacci sequence where each number is the sum of the previous two numbers to increase the size of the spiral. 1,1,2,3,5,8,13,21,34 and so on. This sequence was first recorded by Leonardo de Vinci