New research suggests the site was the scene of a massive celebration which saw guests dine on astonishing amount of shellfish. Experts believe limpets and periwinkles were cooked at the Iron Age feasting site and the shells were thrown into the pit. 

18,637 shells have been found discarded in the pit, believed to date from 300AD to 800AD.

Most shells analysed by UHI Archaeology Institute Masters student Holly Young, were limpets. 

The Cairns Iron Age site in South Ronaldsay was used around 1,500 years ago during the 5th or 6th century AD.

Martin Carruthers, site director at The Cairns and lecturer at University of the Highlands and Islands Archaeology Institute, said: “This is an astonishing number of shells for a short-lived, single-event context.

“This suggests it may have been part of a special food event, a feast involving the whole community of the site or even beyond.”

He added: “One of our project research aims has been to investigate the role of souterrains and this extraordinary contemporary feasting is adding to our picture that souterrains may have been very special places involving social and ritual practices, in addition to whatever other roles they may have had in food production or storage.

“Indeed, during the construction of The Cairns souterrain another cache of shells was placed over the slab roof of the structure along with a special deposit of rotary querns.”

READ MORE Boris erupts at SNP over ‘weapons of mass murder’ accusation – VIDEO