Haliotis Iris paua on turned wooden base

Haliotis iris, or "paua" in Māori, is as much a marine ornament as it is a subject of study. Presented here on a turned wooden base, this shell from the New Zealand coast reveals a natural iridescent sheen that is unique in the world, a palette ranging from cobalt blue to emerald green, sometimes crossed with pink or gold reflections. Both sides of the shell, both oval and convex, are symmetrically curved.

In marine taxidermy, the preservation of these shells involves delicate cleaning, respecting the internal microstructures that participate in the diffraction of light. This magnificent iridescence is due to the layered structure of calcium carbonate (aragonite).