What is the Fibonacci Sequence? Fibonacci sequence is a list of numbers where every number is the sum of the previous two. The Fibonacci sequence starts at 1 and grows infinitely: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55 …

How does it relate to Ammonites?Ammonite shells are a naturally occurring example of the Fibonacci sequence. If you draw a quarter circle in each Fibonacci square, they connect to form an ever increasing spiral. Try to find the Fibonacci squares in your ammonite fossils – photocopy the fossil, then start at the very center by drawing two small boxes right next to each other. With most fossils, the first boxes are .25 cm by .25 cm. Continue drawing boxes with Fibonacci dimensions. You’ll notice that the spiral of the shell always falls within the Fibonacci squares.