This is a fève for you to hide inside a galette des rois, a traditional French treat served to celebrate Epiphany. It comes in a card box, complete with cardboard crown for you to decorate and suggestion of where to find a good recipe. Whoever finds the fève in their slice of galette becomes king or queen for the day and wears the crown. It is approximately 4cm tall.
Here is a good verion of the history of galette des rois.
Obviously there is a choking hazard so I don't recommend giving this to tiny children and warn your guests about the feve.