A high school was evacuated after a student brought what was feared for the first time as an unexploded shell.
Police were called to Alderman Peel High School in Wells-next-the-Sea, but discovered that the article was a "very old piece of metal," said the principal.
Demining experts were first summoned to the school, the Norfolk police said, but did not visit the scene.
Director Alastair Ogle said that the school "has been shown cautious" because of concerns about the item being very rusty.
"A boy brought a piece of metal – a very old piece of corroded metal – that he had found on the beach," he said.
"We did not know if it was something that should worry us."
The school decided to evacuate staff and students from the buildings after finding the object around 10.25 local time, before the police confirmed that it was not not suspicious.
People were allowed to go inside an hour later.
Mr. Ogle stated that the officers took away the object and "congratulated" the school for its actions.
He added that the student had not acted maliciously, but that he had brought his discovery of the beach to "show his friends".