NAGAK: Korean musical instrument
https://worldhitz4u.blogspot.com/2014/10/nagak-korean-musical-instrument.html
The nagak is a
large seashell that is performed as a horn in the traditional music of Korea. The
musical instrument manufactures only a single tone and is mainly used in the military procession music known as daechwita.
The
shell of the musical instrument is that of a very large sea snail, called Charonia
tritonis,
sometimes called "Triton's trumpet". This shell is as well used as a
musical instrument in so many other nations.