I wrote some time ago about structural colour.
More now on that theme.
Some creatures, such as butterflies of the Papilio genus, have sculpted multilayers on their scales: that is they have 2d shapes (for example,like golf balls or dimples) in arrays that maybe interlinked.
Light reflecting off the bottom of the depression (which acts as a 1D structure) is of a different wavelength (and hence colour, say yellow) to that reflecting off the walls (also acting as a 1d structure), say blue. At a far distance the two colours, yellow and blue seem to mix and give the impression that the wings are green!
Another very neat example of structural colour!