At the bottom of an abandoned mine shaft in remote hills, Ioan Lord is shocked to see a tiny pair of boot prints next to his own in the darkness.
They look fresh, but were made 200 years ago - by child miners, the last people to set foot in the passage.
The student, 24, from Ceredigion, has made it his mission to rediscover long forgotten mines in Wales.
Their existence and whereabouts have been lost from knowledge for hundreds of years.
"It's very much like an Indiana Jones film," said Ioan, who has uncovered ancient objects, some dating back to the Iron Age.
"The difference is I don't fly to these locations, I just walk to them.
"There's over 1,000 mines in mid Wales altogether. I can only say I've been into 300 or 400 of them. There are hundreds that are still lost."
Ioan, who is studying for a PhD in the social history of metal mining in south Wales at Cardiff University, is the first person in hundreds of years to access many of these sites.
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What appeared to be a wooden salad spoon he found deep underground was later confirmed by academics to be the oldest complete wooden mining tool ever found in Wales.