The first sound that was heard at the time of evolution was omkaram. Omkaram is the source of all sounds in the universe. Sanku or Sankham produces the omkaram sound. This instrument produces only one sound - Omkaram. Sanku (conch) is a must for all temple rituals and instrumental music. The conch and the sound that the conch produces are considered holy and extraordinary. From ancient times during wars and temple conflicts, the conch has played an important role. The conch is necessary to wake the God, and thereby create a serene ambience. Instruments played during rituals begin and end with the sound of the conch. Panchavadyam and Kathakali begin with the sound of the conch.
Sanku are marine fossil remains. They are shell of molluse, animals of the sea shore with soft bodies devoid of any bone but having hard shells.
Sanku are mainly of two types- Idampiri and Valampiri. This is based on the coiling, if the left oriented coiling inside it is Idampiri sanku and rightward coiling, the Valampiri sanku. The Idampiri sanku is used as an instrument and Valampiri which is rare, is not used as puja material or instrument.
Belonging to the caterogy of wind instrumnents, and based on its shape that is pointed at the top, it is usually blown from the low pitch, gradually increasing to a high pitch by blowing full breath. And, the music fills the air, becoming one with Nature.