For matchlock musket, probably 18^th century. 3 ½” length, natural cow horn shaped to oval section with horn pinned wood base and black lacquered key form filler plug. The tip shaped to seat the end curved end of a horn band which is lashed above the spout forming a fulcrum. The band continues in a shallow “ear” form and penetrates the horn below the base locking to a key slot on the opposite side.  The flask is operated by pressing the horn “ear” which causes the seated tip to pivot and raise from the spout, discharging the priming powder. As charming as it is inventive and the only such mechanism we have encountered personally or in research.