A GIANT prehistoric clam shell weighing more than a quarter of a tonne is to be auctioned in the region.

The fossilised shell was found in Kenya, far inland from the current coastal region and is an ancestor of today’s giant clams.

Living in tropical seas from two to ten metres deep, the ancient clams lived on algae that photosynthesised in sunlit shallows. But approximately 180,000 years ago, during the later Pleistocene era, sea levels rose by 20 metres, reducing the amount of light reaching the sea bed and starving the giant clams into extinction.

The fossilised clams are often found by miners excavating limestone, but now specialists and local miners use technology to locate clams in their mines. This one was found using Ground Penetrating Radar.

Now the shell is to go up for auction at Tennants Auctioneers fine art sale on March 17, alongside an 8cm diameter spherical “pearl” made from a broken piece of shell.

The giant shell will be auctioned with an estimate of £7,000 to £9,000 plus a 24 per cent buyer’s premium, and global interest is expected. The vendor will donate 20 per of his sale proceeds to a women’s outreach project in Kenya.

A spokesperson for the auctioneers in Leyburn said: “It is very rare to find a clam with both sides of the shell still attached, and at 110cm across, it is certainly an impressive specimen.

“Single shells are highly coveted by interior designers who often make them into luxury and unique sinks and the lustrous shells are prized for their decorative qualities in the Far East.”