A MULTI- MILLION- year- old marine mollusc has come out of the limestone and into the limelight with the discovery of a fossilised ammonite on the beach between Christchurch and Highcliffe.

Petrified in the Portland stone of Dorset's Jurassic coast since it sank into the primordial soup some 100 million years ago, the ammonite was revealed when coast protection engineers dumped the chunk of rock on the beach at Steamer Point.

The large limestone boulder split in two, perfectly exposing the intact ammonite at the foot of the public path leading to the Steamer Point beach from the Friars Cliff promenade where thousands of visitors were fascinated by the fossil over the weekend.

"I have never seen anything like it before," said Polish-born care worker Magdalana Klag.

Ammonites existed in the sea for more than 300 million years from the dawn of life in the silurian Devonian eras until disappearing with the dinosaurs at the end of the cretaceous period 65 million years ago.

The distinctive coiled-shell creatures, closely related to modern molluscs such as squid, are among the most commonly found fossils and occur often in the jurassic limestone rock of the Dorset coast.

The Steamer Point example, measuring 65 centimetres (two feet) in diameter, is typical of the Titanite species of ammonite found at Portland where the limestone rock was formed from the sea bed sediment laid down over millions of years.

Originally destined to shore up the rock groynes on the beach, the boulder bearing the ammonite will be removed in the next few days and safeguarded as an added attraction at the nearby Steamer Point clifftop woodland nature reserve where the fossil will be displayed outside the information centre.