The auger shell whistle.
Daniel W. Zietlow, Thomas R. Moore · The Journal of the Acoustical Society of America · 2009
We report on investigations of a musical instrument made from the shell Terebra Turritella, or auger shell. To our knowledge, this instrument has been developed only recently. The instrument is played from the large end using an edge tone, and a diatonic scale is achievable merely by drilling five tone holes in a straight line down the length of the spiral shell. It is surprising that a naturally occurring cavity can produce a diatonic scale, and implies that there is something special about the shape of the auger shell. However, experimental and theoretical investigations reveal that the auger shell does not actually have such a resonance structure.