They were the deadly weapons that struck fear into the hearts of sailors and fishermen as they worked off the wartime north-east coast.
But now a former Second World War sea mine in Aberdeen is to be transformed into a special charity box to raise funds for struggling former seafarers across the city.
The bomb, after being taken from the sea and decommissioned, has sat for decades near a play park in the Footdee area.
But following a visit by Aberdeen’s Lord Provost Barney Crockett to the annual general meeting of the Shipwrecked Mariners Society, it emerged the mine had been temporarily removed and transported to a workshop for renovation.
A granite plinth will be added and it will then be given pride of place at the harbourside, with an opening through which coins and notes can be dropped.
Justin Osbond, chief executive of the society, said the formerly deadly ordinance would now be used to help struggling seafarers in the granite city.
He said: “The sea mines were taken on by the society some time ago as they were being decommissioned by the Royal Navy.
“We have preserved them and they are being placed across the country to help us raise funds.
“We support about 1,400 people and have quite a big footprint in Aberdeen.
“It was fantastic for the Lord Provost to come along and offer to help with Aberdeen’s mine.”
Mr Crockett said: “When I was at the conference I discovered there were a network of mines around the coast but I noticed Aberdeen’s was missing from the list.
“When I looked into it, I found out it was being taken to a workshop to be restored to its pristine glory and reinstated at the harbour.
“It would have been terrifying heading out to sea during war time, never knowing what lay beneath you.
“This will prove a fitting tribute to our city’s strong maritime heritage.”
The project is being funded by a mystery benefactor.
The society is celebrating its 180th anniversary. It provides £1.4 million in support each year.