Algolian musical instrument
From Memory Alpha, the free Star Trek reference.
An Algolian musician was abord the USS Enterprise-D during the biennial Trade Agreements Conference and entertained the visitors of Ten Forward by playing his instrument.
William Riker later transmitted the rhythm by subspace as a covert distress signal from the Ferengi ship whose crew had kidnapped him and Deanna and Lwaxana Troi. (TNG: "Ménage à Troi")
