From BostonGlobe.com…..
On a hot July afternoon, Arthur Flynn III was on a kayak when he dropped a large magnet attached to a rope into the murk of the Nashua River.
The 60-year-old from Ayer was floating near Fort Devens when he pulled up an unexpected catch: an MK-2 “pineapple” grenade and a 60mm mortar shell.
He was soon met by State Police and a local bomb squad.