Just as the wonder-working mantle of the Nautilus changes the material it absorbs from the water and makes it a part of itself, so the bits of knowledge one gathers undergo a similar change and become pearls of thought.
In the Coralline Limestone the following fossils have been noted :- Spondylus, Ostrea, Pecten, Cytherea, Arca, Terebratula, Orthis, Clavagella, Echinus, Cidaris, Nucleolites, Brissus, Spatangus; in the Marl the Nautilus zigzag; in the Yellow, Black and Greensand shells of Lenticulites complanatus, teeth and vertebrae of Squalidae and Cetacea; in the Sandstone Vaginula depressa, Crystallaria, Nodosaria, Brissus, Nucleolites, Pecten burdigallensis, Scalaria, Scutella subrotunda, Spatangus, Nautilus, Ostrea navicularis and Pecten cristatus (see Captain Spratt's work and papers by Lord Ducie and Dr Adams).
In Nautilus two pairs of auricles are present, corresponding with the two pairs of ctenidia.
Assuming that these ancestral forms resembled the existing Nautilus in their internal anatomy, they had two pairs of renal ducts and one pair of genital ducts, which would apparently indicate, not a single metamere or unsegmented body, but three metameres.
The shells of the pearly nautilus are commonly used by the Visayans for drinking cups.
Like noiseless nautilus shells, their light prows sped through the sea; but only slowly they neared the foe.