The conch ( chank shell or Shankha) has special significance in the Hindu tradition. The conch represents the sky and the sound it produces represents the pranava i.e. Om. When a person blows a conch, it gives him the effect of doing a pranayama. Lord Vishnu carries a conch called Panchajanya in his left hand. Goddess Durga also carries a conch as a decoration and also as a tool in war. The warriors of ancient India blew conch shells to announce battle. According to some legends, Lord Vishnu touched the right cheek of Dhruva by his divine conch and that sparked off a beautiful poem of praise of the Lord called Dhruva-stuti.
The water from a conch is supposed to be as sacred as water from Ganges and other sacred sources. If the conch is shaped in such a way that it opens towards the left side, it is called Vaamavarti Shankhas and is considered as fit for regular use during prayers to blow through it. It is considered as Devi swaroopa. In fact, most of the conches are Vaamvarti, that is, their bulge opens towards left side. But if it is right sided, it is more sacred and is called Dakshinavarti Shankhas considered fit for worship as Vishnu swaroopa and is not used to blow.