Vintage prosthetic thumb digit, poss, WWI ?!

Strange thing I bought many years ago at an antiques fair! I was told that it was a prosthetic Thumb digit possibly dating from WWI. It has been painted a skin colour and has been made to look like an authentic thumb. It is made from some type of silver coloured metal. Some of the paint has inevitably chipped at the bottom - please see photos. A great item for your curio cabinet!