Amongst hundreds of thousands of muddy spuds, a World War II era grenade was picked up on a conveyor belt at an Auckland potato factory earlier this week, RNZ reports. The old Mills bomb grenade, which has since been confirmed as being a training grenade which didn’t contain explosives, is believed to have been dug up during harvesting on a farm in Matamata. Mr Chips factory operations manager Roland Spitaels said there had been a number of army training camps held around the Matamata area.