A man who turned up at the Dunedin Central police station with what he thought was a bomb sparked a call to the police bomb squad.
The Good Samaritan arrived in the station foyer about 10.45am on Sunday, carrying a ''rusty, spherical, metal ball'' that he thought might be a bomb.
It was not known where the man got the item from.
Sergeant Steve Aitken, of Dunedin, said it was similar in size to a car or truck towball.
''That created a little bit of consternation for a while.''
Sgt Aitken said the apprehensiveness of police was not so much that it might have been a bomb, but that police were about to have about 1000 people arrive for the police open day.
The station was not evacuated.
Photos of the object were sent to an ''army explosives expert'', who quickly assured police it was not dangerous. He retrieved it and disposed of it yesterday.
''The determination was made pretty quickly that it was not explosive [and] it was put in a secure area.''
Finding explosive devices in Dunedin was rare, with about one or two cases a year reported, Sgt Aitken said.
''We have had instances where old hand grenades have been dug up in gardens,'' he said.
Sgt Aitken had some advice for people who came across something odd-looking and thought they might have discovered a bomb.
''If people suspect something of an explosive nature, please don't pick it up.
''Old explosives can be unstable and movement can detonate them.
''If you move it, it could be that last straw to make it go [so] leave it, photograph it [and] don't bring it in.''