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Pronounced – Am-mon-nite
Meaning of name – The shell resembles the coiled ram’s horn (a ram was the symbol for the Egyptian god Ammon)
Group – Cephalopods, Mollusc
Age – Lower Jurassic, around 195 million years old

Ammonites are a well known fossil and easily recognised by their coiled shell. They first evolved around 240 million years ago and became a very successful group of animals. They died out around the same time as the dinosaurs about 65 million years ago. Ammonites were free swimming creatures related to squid and octopuses. Like these modern relatives they would have been predators, catching prey with their long arms. Their shell was divided up into chambers filled with liquid and gas, which kept them buoyant in the water. They can be preserved in a number of different ways.

Calcite split

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This calcite ammonite (Promicroceras sp.) has been found by splitting one of the layers of hard limestone rocks with a geological hammer. You should always wear goggles when hitting rocks and ask at the Heritage Centre for advice on how to find them.

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