Fossil Favourite Stamp
Artist's impression of a living ammonite
Artist’s impression of a living ammonite

Ammonites  – the ultimate jet-propelled shells!

  • Ammonites are extinct marine creatures – and some of the most commonly found fossils.
  • They scooted through the warm, shallow seas by squirting jets of water from their bodies. So they jet-propelled themselves – backwards!
  • Ammonites have a spiral shell divided into chambers. When the animal was alive, it could fill the chambers with gas and water to move up or down.
  • Only the shells of ammonites have ever been found as fossils. Some are as big as one metre across!
  • We know lots about ammonites because their closest living relative, the nautilus, still survives today in the Pacific and Indian Oceans.
  • Ammonites were food for creatures such as ichthyosaurs and pliosaurs. Some ammonite shells have bite marks from these marine monsters.
  • In England, particularly around Whitby, people once thought that ammonites were coiled snakes that had been turned to rock. So they were known as snakestones.
  • Admire this elegant ammonite in Bridport Museum.

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