As celebratory feasts go, the menu choices do seem to have been rather limited. 

However, new research into an Orkney Iron Age site suggests it was the scene of a massive prehistoric party, which saw the guests tuck into an astonishing amount of limpets and periwinkles. 

More than 18,600 shells were found in a pit at The Cairns site, at South Ronaldsay. 

Now radiocarbon dating technology has shown the pit was used in the fifth or sixth century AD, apparently to cook the shellfish before they were handed out to hungry guests. The shells – all 18,637 of them - were then put carefully back into the pit, perhaps as cooks and guests tidied up after their get-together.

Experts believe the shellfish supper was a single event, presumably attracting a high number of invitees with a hearty appetite for limpets and periwinkles.

“This is an astonishing number of shells for a short-lived, single-event context,” said site director Martin Carruthers, who is leading a team of researchers at the site from the Archaeology Institute of the University of the Highlands and Islands. 

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

The Cairns is an Iron Age settlement on a hillside overlooking Windwick Bay in South Ronaldsay. Archaeological investigations have been carried out at the site for the past decade. 

Work this year is intended to focus on how brochs were used and how the broch setting at The Cairns is influenced by a Neolithic mound at the site.

However, research at the site has previously revealed a fascinating insight into Iron Age life, including the discovery of a spectacular carved whalebone vessel containing a human jaw bone complete with teeth. It was found alongside two red deer antlers and a broken saddle quern, apparently all carefully laid out in a particularly symbolic fashion.

DNA testing revealed the bone to be from a giant fin whale, the second largest species on the planet after the blue whale.

Its discovery, next to the entrance to the broch, suggested the items were of high importance to the site’s inhabitants – possibly placed there as part of the ceremony surrounding its abandonment.

The find sparked debate among archaeologist as to whether Iron Age people would have been able to hunt such large whales or whether they had to rely on harvesting animals stranded in shallow water.

The site has revealed around 100 pieces of bones from whales and other cetaceans – making up one of the world’s largest collections of prehistoric whale bones.

A number of carved stone discs have also been found, which are thought to be gaming pieces or counters – providing an insight into the leisure time and social lives of the Iron Age inhabitants. 

While recent discoveries have included perforated bone artefacts which appear to be parts of a horse-harness, and ancient glass fragments.  However, one, a dark-green shard of glass, is thought to have come from Roman glassware – creating a mystery of its own. 

“It’s impossible to know if our shard represents a down-the-line exchange, or direct access and interaction with the Roman world,” said Mr Carruthers. “The types of Roman material in Atlantic Scottish Iron Age sites, however, seems to suggest that there’s a definite appetite for the higher status Roman trappings such as jewellery, Samian ware and glass vessels.

“To me this suggests they’re not just taking whatever they can get their hands on but have agency enough to source the goods and objects they want.”

The shells at the pit – which make up over half of the total number of shells found at the entire site so far - were analysed by UHI Archaeology Institute Masters student Holly Young. They were found to be made up of 84% limpets with common periwinkles making up the rest. 

The radiocarbon date shows the pit was being used at the same time as a nearby souterrain or ‘earth house’.

Mr Carruthers 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.”