Phi does show up in other aspects of nature.
It’s true that nautiluses maintain the same shell proportions throughout their life, but the ratio of their shells is usually a logarithmic spiral, as opposed to an expression of phi. Some seashells expand in proportion to the golden ratio, in a pattern known as a golden spiral, but not all shells do. The proportions of nautilus shells and human bodies are examples of the golden ratio in nature, but these tend to vary greatly from one individual to the next. Golden ratio enthusiasts argue that the golden ratio is aesthetically pleasing because it’s common in the natural world.
