The romanesco cauliflower is one of the many examples of a Fibonacci fractal in nature. The Fibonacci sequence starts like this: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55 and so on with each number being the sum of the two numbers that precede it. The cauliflower’s whole head is made up of smaller heads that mimic the shape of the larger head, and each of those smaller heads is made up of even smaller similar heads. 

I did not realise that I had already blipped a romanesco cauliflower before with a much better explanation.