Dr David Williams, a research associate based at Cardiff University’s School of Engineering, said he was “sceptical” when he was asked to use a scanning device to try and solve the mystery.
“It’s challenging, the device we have is not designed to this particular purpose,” he said.
“This is micro CT scanning, something you’d get at the hospital, but for smaller items.”
Williams said he was “always open to a challenge” and trying to “figure out a puzzle”.
“We did a first scan to see if we could see anything and we were quite surprised that we could see letters,” he said.
“The second scan went terribly, but with the third scan, we tried a different approach, and figured out the code.
“I was blown away that we actually cracked it.”