Marine scientists are offering a reward for the return of a £3,000 shark tag which has been tracked across Scotland's central belt.
The tag has been tracked to a number of inland destinations
The device is believed to have come off a basking shark in the Firth of Clyde.
Scientists believe it was picked up by someone who lives in Ayrshire and is being kept in a bag.
They want it returned as it contains crucial data about the movements of a shark between the Isle of Man and the West Coast of Scotland.
Dr Mauvis Gore, who is part of a project run by Marine Conservation International, said the purpose of tagging was to track the sharks once they headed north from the Manx coast.
She said: "This one seems to have chosen to go into the Clyde, then the tag has come off. Now it's a bit of a mystery.
"It seems to be moving back and forth between Ardrossan and Troon and we think it's based in Irvine.
"But it has also gone on 'holiday', one day to Edinburgh and back."
Dr Gore said she believed that someone had the tag in a bag or possibly the boot of a car.
"We have a reward as the tag is valuable from a data point of view," she said.
"If we can get it back then we can trace what the shark has been doing since it left the Isle of Man.
The tag is thought to have come from a basking shark
"We want to know how deep it has gone, what area it needs to be in, so that we can see what type of water these basking sharks prefer.
"For a big animal like that, we actually know more about its tiny food (plankton) than we do about the shark itself."
Dr Gore said the project was "desperate" to recover the tag, which she described as being "like an ice-cream cone".
She said the cone part would look grey with the ice-cream part being bright red. It also had an antennae sticking out the top "like a 99".
Dr Gore asked anyone who finds the tag to send it to the University Marine Biological Station at Millport.