Mitchell (who does not wish his surname to be used) said he was at Delicate Beach on Monday with his partner and their children when two-year-old Kieran chased a lizard into a pile of rocks.

“He loves his lizards - we have a legal pet blue tongue goanna at home, and he is always looking for them,” Mitchell said.

“He flipped over a rock found what we thought was just a bit of plastic, but he wanted to keep it so we put it into his special pile with his shells and stuff and I didn’t think much of it.

“Then, further down the beach, he flipped over another rock and underneath it was a key also sealed in plastic.

“I looked at the original stuff that he found and it was a piece of cardboard with a series of numbers sealed up in exactly the same way.

“This was too much of a coincidence, so we went back and looked in the original spot where he had found it and within a few minutes we came up with another piece of cardboard, sealed in plastic with the same code letters on it.

“It was bizarre.”

Mitchell researched the find on the internet originally thinking that the find might have been part of the activity known as ‘geo-caching’, which is a type of treasure hunt using GPS co-ordinates.

What he discovered was that the key was for a type of small safe which is sold at hardware stores.

“I rang the manufacturer (Sandleford) and they confirmed that the key and the codes were consistent with one of their products,” he said.

“I am going to hand them in to the police in Kempsey so they can deal with it.

“It might be completely innocent but it all seems a bit strange to us."