Bomb disposal experts turned up at a museum volunteer's Norfolk house after he took home some grenades found in the museum's archive.
Volunteers at Bishop Bonner's cottage in Dereham found a box labelled "bomb" while sorting through items held in storage.
They opened the box and found three clay balls packed with gun powder with wicks sticking out of them.
Bob Davies, Vice-Chairman of the Dereham Antiquarian Society, decided to take them home.
He added that experts were so impressed by the find that they will find a new home for the grenades in the bomb disposal unit's museum in Colchester.