Add the second 1 and 2, for 3. Add the 2 and 3, for 5. Or spiral, as in the Daisy. You've also seen this proportion when you've drawn the five-point star . Each intersection of a segment by another segment in it divides the intersected segment in the golden proportion.
More complicated forms occur when multiple bubbles are joined together.
But it is not yet know if the Triple Bubble is area-minimizing .