Nautilus pompilius; Print; The chambered nautilus; Nautilus pompilius; also called the pearly nautilus; is the best-known species of nautilus. The shell; when cut away; reveals a lining of lustrous nacre and displays a nearly perfect equiangular spiral; although it is not a golden spiral. The shell exhibits countershading; being light on the bottom and dark on top. This is to help avoid predators; because when seen from above; it blends in with the darkness of the sea; and when seen from below; it blends in with the light coming from above.