Multiple hand grenades have been washing up on the beach in Newport, Oregon. The Newport Police Department issued a warning statement: "These devices are white in color and have a label attached to them that reads "Warning Explosive". The label clearly states the item is a Simulator Hand Grenade M116A."
According to a marketing brochure for the M116A, the grenade "is designed for training exercises to acclimatize troops to the sights and sounds of battle in a non-lethal format. This device, once the pull-wire is activated, after 6 – 12 seconds produces a loud report or simulated explosion of a grenade."
A YouTube search for the M116A turns up the following: