Fibonacci numbers are important

Fibonacci numbers explain how things expand and why they give rise to spirals.

You can find Fibonacci numbers all over the natural world. The number of petals on a flower is a Fibonacci number. Cut open a fruit, and you'll find a star shape with a Fibonacci number of arms. A banana has a three-pointed star, and apple a five-pointed star. The cells on a pineapple have several Fibonacci numbers.

If you take squares whose dimensions correspond to the Fibonacci numbers, then you can arrange them in an expanding rectangle.