By CHRIS BROOKE

Last updated at 19:28 15 April 2008

During the ice age it adorned a fearsome woolly mammoth.

Reappearing from the mists of time, the 4ft-long piece of tusk was washed up on a Yorkshire beach.

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Connor Clark, Blousy Haorang and Arachai Haorang hold the woolly mammoth tusk they found at Spurn Point in Yorkshire

There it was spotted by Arachai Haorang, 13, his sister Blousy, nine, and their cousin Connor Clark, ten, during a family walk along Spurn Point.

At first they thought it was a piece of driftwood but when it was too solid to break on a rock, one of them suggested it could be a dinosaur or whale bone.

To their amazement, they weren't far off.

They carried the tusk - weighing around 60lb - to a nearby visitor centre and the site warden knew immediately they had discovered a historical treasure.

Andrew Gibson, from the Yorkshire Wildlife Trust, said: "I knew instantly what it was. I could tell from its size, weight and curvature that it was a tusk.

"It's incredible to think that when they picked it up they would have been the first in

50,000 years to have touched it."

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Mammoth tusk: Dates back to the last Ice Age when the North Sea was land and Mammoths grazed there

The tusk is between 12,000 and 75,000 years old and a conservator who is now carrying out preservation work on it has estimated that it comes from the "older end of the time period".

Mr Gibson said a ten-inch piece of tusk was found in 1996 at Spurn Point, a three mile-long finger of land at the mouth of the Humber Estuary.

But discovering such a huge section of woolly mammoth was "extremely rare".

'"It dates back to the last ice age when the North Sea was land and woolly mammoths grazed there," he said.

Arachai and Blousy's mother, Diane Haorang, 37, as well as her her brother and father, were all present when the tusk was found.

Mrs Haorang, who runs a carpet cleaning business with her Thai-born husband, said: "The children are all very excited about making such an amazing discovery."

A more complete but similar length Siberian mammoth tusk was sold two years ago by Sotheby's for £6,000. The Spurn Point tusk will be returned to the wildlife trust's visitor centre for future generations to appreciate.

Meanwhile, the young beachcombers have become keen treasure hunters. The next weekend they returned to the same area and found a bone, thought to come from an ice age elk.