WASHINGTON (DC News Now) -- Magnet fishermen in D.C. made a surprising discovery on Sunday. Magnet fishing is when people throw large, heavy-duty magnets into bodies of water to see what sticks. The Metropolitan Police Department (MPD) told DC News Now that just before 3:20 p.m., officers responded to the area of Theodore Roosevelt Island after the department received reports of "an object resembling a grenade" that had been pulled from the water. ‘Magnet fishers’ pull bikes, scooters from Anacostia River in Navy Yard The Explosive Ordnance Disposal Team quickly responded to the scene and, after examining the object, determined it was inactive. The "object resembling a grenade" that magnet fishermen pulled from the Potomac River on Sunday, Dec. 22. (Courtesy: Kevin Sutliff)The "object resembling a grenade" that magnet fishermen pulled from the Potomac River on Sunday, Dec. 22. (Courtesy: Kevin Sutliff) The magnet fishermen who discovered the object are the same fishers who pulled bikes and scooters from the Anacostia River last month.