A unique prehistoric carved stone ball, said to be so rare it is priceless, has been stolen from a Scottish museum.
The ball - which is about 6cm across - was taken from its display cabinet at the volunteer-run Dunblane Museum while curators' backs were turned.
Museum curator Marjorie Davies said the theft was "shocking" as the ball was irreplaceable.
Known as a petrosphere, the ball was originally found near Dunblane about 100 years ago.
The museum said the ball had been taken in November, and initially staff tried to trace it by circulating details to other museums. Police have only just been called in.
Mrs Davies said: "It's big enough to hold in your hand, but you wouldn't be able to close your hand round it.
"These things are unique to Scotland. They tend to be found in the north of Scotland."
She said that scholars could not decide what they were used for or why they were made.
"They are very, very rare, and anybody who tried to sell it would immediately have to furnish the provenance of it," she added.
"You certainly couldn't put a price on it."
Police in Dunblane said they were investigating the theft and appealed for information.
A spokesman said: "If you have any knowledge of who may be responsible or know the whereabouts of the stone ball, please contact Dunblane officers on 101 or via Crimestoppers on 0800 555 111."