Archaeologists on the Orkney island of Rousay have uncovered the preserved handprint of a Pictish metalsmith.
They found the print on a stone anvil excavated from a substantial Iron Age settlement. It is believed to be at least 1,000 years old.
The site's co-director told BBC Radio Orkney she believed the print was unique.
Volunteers are racing to excavate the site, known as the Knowe of Sandro, before it is eroded away by the sea.
Hands and knees
At first, the archaeologists thought they were looking at one of their own handprints, left on the stone anvil as they lifted it from the Iron Age metal workshop.
But closer analysis showed that the blackened imprints came from the hands and knees of the metalsmith himself.
They believe he forged brass and other metals in his dark underground workshop at some time between the 6th and 9th centuries.
Dr Julie Bond, co-director of the dig, said: "We were taking up the two stones that were used as anvils. When they were cleaned, we noticed that one of them had what looked like handprints on.
"I have never seen anything like this before. It's unique as far as I know.
"Knowing that this is a Pictish building, I would guess the prints are somewhere between 1,000 and 1,500 years old."
The smithy was entered via steps and a curved corridor, minimising the amount of light entering the room and allowing the smith to assess the temperature of the hot metal based on its colour.
The centre was dominated by a hearth and two stone anvils.
The building is part of a substantial Iron Age settlement which is being slowly destroyed by the sea.
The Swandro Orkney Coastal Archaeology Trust has been working to uncover the site since 2010.