This must be old currency from the Onokiwans who journeyed through Norrath. When playing hide-the-shiny, younglings cover their eyes while one hides the coin in the cave. The rat who hid the coin will shout, 'Nikao mi,' and the rest of the younglings run and search for the coin.
This item is a part of the collection: Onokiwan Toys (Firefall Pass).