Examples of Fibonacci sequences and numbers in nature are spiral shell formation, rabbit population and various parts of human anatomy. Many natural occurrences of the Fibonacci sequence are represented by the golden ratio, or the limit of the ratio of each Fibonacci number to its successor.
Spiral shells are a series of connected quarter-circles drawn inside squares whose dimensions are all Fibonacci numbers. The squares are arranged in a circular formation and fit perfectly together. Rabbit population is represented by modeling the number of rabbits each couple produces in a given period of time. The average total rabbit population estimates come out as Fibonacci numbers. Examples of the Fibonacci sequence in human anatomy include proportional sections of fingers, human size and cochlea shape.