Phyllotaxis
the spirals are counted, not admired
Generator

raup-shell

W·D = 1.01, so the whorls are free of each other — an evolute shell, like a ram's horn or a planispiral ammonite. Both are things animals grow.
A shell section at W = 2.40, D = 0.42W·D = 1.01, so the whorls are free of each other — an evolute shell, like a ram's horn or a planispiral ammonite. Both are things animals grow.W = 2.95 · D = 0.42W·D = 1.24 — evolute

Drawn at its defaults, in shells and growth. It carries a slider over Wp, so the claim in its caption strip is restated at every stop rather than at one. It takes no options at all, so every essay calling it gets this exact drawing.

Called by 1 essay

the blast radius of changing it

Shells and growth

Raup's three numbers

Nearly every coiled shell that has ever existed is a point in a three-dimensional space — how fast the whorl expands, how far the opening sits from the axis, how far it travels along it. That is a remarkable compression, and the most useful line in the space is the one where the whorls come apart.

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