Chambered Nautilus - Nautilus pompilius
Shells of the Chambered Nautilus, Nautilus pompilius (Nautilidae) are formed by two layers. The external layer has a pattern of irregular brown to reddish brown stripes, while the inner layer (as seen in the photo) is striking white iridescent.
The iridescent material inside nautilus shells is sometimes machined into pleasing shapes and sold as “Osmeña pearl.”
Photo credit: ©Maciej Bledowski