The Palau nautilus is a nautiloid endemic to waters around Palau. It is a large species, second in size only to giant specimens of Nautilus pompilius which is highly variable in size. Although very similar to Nautilus pompilius, it is differentiated based on fine raised ridges along growth lines of the shell and difference in the radula (the colour of pattern is also usually much lighter). It may, however, become recognized as a subspecies of Nautilus pompilius or its synonym in the future as genetic data seem to suggest.