The 500 pound World War Two device was picked up during dredging work.
Burglar Raids Dorset School Changing Room
Police in Sturminster Newton are investigating a burglary at a school in the town.
It happened at around 5.05pm on Wednesday 3 July 2013 at Sturminster Newton High School on Bath Road.
A member of staff alerted Dorset Police when they found someone in the changing rooms. They ran off through a fire exit, making off with mobile phones and iPods.
Inspector Shawn Whitley, of North Dorset police, said:
"The individual responsible has entered the school and made off with a quantity of high value items.
"I am appealing to anyone who may have witnessed a man acting suspiciously in the area prior to the incident, or has details of his identity to contact us in confidence.
"I would also like to speak with anyone who may have seen two suspicious vehicles make off from outside the school just after the incident occurred.
"We believe these to be a small white car or van and a blue Peugeot."
No arrests have been made.
Witnesses and anyone with information should call Dorset Police in confidence on 101.
640 men were killed when the South African troop carrier was hit by a cargo ship in 1917.
The 79-year-old man suffered a serious head injury in the Cranmer Road car park in Winton.
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