Chambered nautilus
（重定向自Nautilus Pompilius）
![](/Images/godic/202501/29/Nautilus-JB-014509.jpg")
![16th-century Northern Mannerist nautilus cup](/Images/godic/202501/29/Milano_-_Castello_sforzesco_-_Nautilus_su_argento_cesellato_-_Germania,_sec._XVI_-_Foto_Giovanni_Dall'Orto_-_6-1-20074509.jpg")
![Nautilus shells engraved to commemorate Horatio Nelson, displayed at Monmouth Museum](/Images/godic/202501/29/Nautilus_shells_to_commemorate_Horatio_Nelson,_at_Monmouth_Museum,_Wales4510.JPG")
![A nautilus shell was used to fashion this drinking cup depicting Atlas, a legendary titan of Greco-Roman mythology.[6]](/Images/godic/202501/29/Dutch_-_Nautilus_Cup_-_Walters_57989_-_Profile4510.jpg")
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.