A picture would be great. Carl is correct, you should call the local bomb disposal unit to make sure it isn't still live. Even if there are no explosives the detonator can still pack a large punch. After that, a museum is your best bet for getting rid of it.

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Please give the Combined Fleet the chance to bloom as flowers of death. This is the navy’s earnest request. RADM Tasuku Nakazawa prior to the Battle of Leyte Gulf
It is the function of the Navy to carry the war to the enemy so that it will not be fought on U.S. soil. Admiral Chester W. Nimitz