Nautiluses are an order of cephalopods that live between 100 to 300 metres down in the ocean. Nautiluses have changed very little during the last 500 million years or so, and where there were once hundreds of species there are now only six that remain today. The nautilus' coiled shell has a series of chambers filled with gas, into and out of which it can pump fluid when it needs to dive or ascend. These shells show some of the most amazing spirals in nature.

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