NAUTILUS - The Solitary floating Pump of the deep

They have not evolved much during the last 500 million years. Many were initially straight-shelled, as in the extinct genus Lituites. 

They mainly developed in the Late Cambrian period and became a significant group of sea predators during the Ordovician period where certain species reached over 2.5 metres (8 ft 2 in) in size.

Abundant in the Middle and Lower Jurassic as well as at the base of the upper Cretaceous the Nautilus floats by pumping gas into their shells which are filled with cameras in order to regulate the float's depth. 

The growth of the radius of their interior's shell obeys to the spiral's logarithmic of the GOLDEN RATIO which is an irrational algebraic real constant denoted by the Greek letter (PHI), in honour to Phideas the Sculptor, which would have used this mathematical scale to design the PARTHENON, with the value rounded to three decimal places 1.618.