Nautilus case

Twenty Thousand whirls under the seas
Nautilus is the last representant of the ancient cephalopod families (animals without backbone but with tentacles or arms), the only living descendant of the ammonites, oceanic creatures that prospered in our seas 500 million years ago, when the continents were still forming. Known as living fossils, they remained unchanged for millions of years, an actually live and hunt along tropical reefs, moving to deep seas during the day to avoid predators. The spiral shaped shell of the Nautilus is divided in chambers: the animal lives in the external chamber, and uses the other ones to move in the column of water. As a submarine it fills and drains the chambers to dive deeper or to rise to shallow waters.