I have a pair of these gruesome skulls. They are about 1.5cm long and 1cm wide. They belonged to my mum and I believe she was given them as a child when she lived in Ceylon (Sri Lanka) to ward off bad luck and spirits.
I remember my youngest brother wearing one of them when he had one ear pierced, but I inherited them both.
I hope they are a man made material (1930's Bakelite perhaps?). Unfortunately she's not here to ask.
@wendyfrost @joysabin hunting around for inspiration turned up trumps!
@summerfield a pleasure