Ammonoids are an extinct group of marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs are more closely related to living coleoids (i.e., octopuses, squid, and cuttlefish) than they are to shelled nautiloids such as the living Nautilus species. The earliest ammonites appear during the Devonian, and the last species died out during the Cretaceous–Paleogene extinction event.
ABOUT LYME REGIS:
Lyme Regis is famous for its geology, fossils and its unparalleled role in the birth of the earth sciences. The local blue lias clay found to the east and west contains the remarkable fossil remains of sea creatures from the Jurassic seas of 180 million years ago.
It was on these beaches that one of Lyme's most famous citizens, Mary Anning (1799-1847), discovered the first complete ichthyosaur to be found in England, and she was just 12-years-old at the time. Through her hard labour and scientific approach to recording her discoveries, Mary established herself as a renowned palaeontologist, and working with contemporaries Buckland, Conybeare and Henry de la Beche, played a pioneering role in developing our understanding of the earth.
The remains of complete ichthyosaurs, plesiosaurs and other incredible sea creatures are found to this day by people of all ages.
The spiral shaped ammonite (a long extinct member of the mollusc family a bit like a nautilus) is more common, and with patience and a bit of luck you'll be able to find your own fossil in the rock pools or among the shingle.
You can also find fool’s gold (iron pyrites), ammonites and bullet-shaped belemnites or trace ammonites in the large boulders - those on Monmouth Beach to the west of Lyme and seen at low tides are particularly impressive, with some being one metre across.