Coloured X-ray of the Nautilus shell

Nautilus shell. Coloured X-ray of the cephalopod shell, Nautilus pompilius. This is the common chambered or pearly Nautilus. The shell is empty of contents, with inner chambers and spiral whorls visible. The external colour of the shell is off- white, with radial bands of a tan colour. The siphuncle tube is clearly seen here, passing from one shell chamber to another; this internal tube fills the chambers with gas and enables the Nautilus to float or sink. There are only 6 living species of Nautilus, descended from a large group which originated in the early Palaeozoic era. The animal resembles a squid in having a foot of many tentacles. It feeds on crabs and carrion.. Stunning Photo Gifts From Science Photo Library