the.com/fibonacci spiral

means A curve traced through squares whose sides follow the Fibonacci sequence, approximating the logarithmic spiral seen in shells, florets, and galaxies.

from Named for Leonardo of Pisa, nicknamed Fibonacci, who introduced the sequence to the West in a 1202 book on arithmetic — though he'd learned it from earlier Indian mathematicians who'd studied it centuries before him. The 'spiral' itself is a later visualization: draw squares with side lengths matching the sequence (1, 1, 2, 3, 5, 8...), tile them together, and sweep an arc through each — the result approximates (but isn't identical to) the golden spiral found throughout nature. The sequence's link to growth patterns in leaves and shells was only widely popularized in the 19th and 20th centuries, long after Fibonacci's time.