It could be a part of 'Sounds of the world' series or an individual stamp, because of the 30 year anniversary of the discovery of the oldest musical instrument in the world. Found in Slovenia in 1995.

This unusual musical instrument, neither a flute nor a whistle, was cemented near the remains of a 50,000 – 60,000 years old Neanderthal fire pit, made from the thigh bone of a young cave bear into which the Neanderthal drilled three holes and made a sharpened rim for the mouthpiece using tools made of bone and stone.

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