Hong Kong police destroyed a German-made grenade from World War I after the device cropped up in a shipment of imported potatoes at a local potato chip factory.

The grenade, described by authorities as having been caked with mud and dirt, was discovered by workers at a factory run by Japanese snack maker Calbee, South China Morning Post reported.

Police said they used a “high-pressure water firing technique” to safely detonate the weapon.

Superintendent Wilfred Wong Ho Hon said the “the grenade was imported from France together with the other potatoes,” CNN reported.

Dave Macri, a military historian, told the Morning Post that the grenade had likely been dug up by accident by potato harvesters in France.