Artificial miniature islands that speckle the waterways of Scotland and Ireland are twice as old as originally thought, scientists have revealed for the first time.

It had previously been thought that hundreds of artificial islets, known as “crannogs”, had been built in the last 2,500 years.

But new research published in Antiquity, an academic journal on the subject of archaeology, says crannogs actually date back to the time of Stonehenge which was built more than 5,000 years ago, and potentially served as ritualistic offerings.

Scientists researched crannogs in the Outer Hebrides, off the coast of mainland Scotland, and now believe they were once “special locations” because pottery has been found littered in the seabed around them.

The findings suggest the sites may have been constructed by transporting and piling massive boulders on top of flat land and it is likely they were then used for ceremonial purposes.

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Many of the ceramic vessels were either still intact or broken into large fragments, suggesting that there was a systematic and ritualised manner in which they were put into the water, according to the website IFL Science.

People built, modified and reused crannogs in Scotland up until the 17th century, according to the Scottish Crannog Centre.