The role of Conch in Hindu Gods
In Hindu religion, Shankh, is of great importance and symbolizes luster, brilliance, purity and auspicious. In India the sound of the conch is associated with the sacred syllable AUM, the first sound of creation. Conches that spiral clockwise are said to symbolize the expansion of infinite space. These conches belong to Lord Vishnu, the preserver god. Conches that spiral counterclockwise are said to defy the "laws of nature," and belong to the destroyer/transformation god, Lord Shiva. The conch is one of the five principle weapons of Vishnu. Followers of Vishnu believe the conch shell was given to us to destroy all evil. Arjuna, the hero of India's epic Mahabharata, blew a particularly powerful conch as a battle horn. It was said to banish evil spirits, avert natural disasters and scare away poisonous creatures.
Lord Shiva once stole Vishnu's conch, but blew the conch so loudly that Vishnu knew immediately who had it. Shiva instantly appeared before Vishnu and explained that the conch was at his home on Mt. Kailash, but it was his son the elephant god Ganesh who had it. If Vishnu wanted the conch returned he would first have to perform a puja ceremony in honor of Ganesh. The Hindu gods are always engaged in these mythic dramas, usually for our benefit. You can hear all of these stories from India's itinerant holy men, the sadhus. When the sadhus sit around a ceremonial fire and smoke ganja in their chillum pipes, before they light up they chant, "Bom Shiva Shankara!" which means "Hail Lord Shiva the Conch Shell Blower!"
A conch (shankha) is blown to invoke Shiva, this is not so in the case of other Hindu deities. The conch is a rather primitive instrument used in tribal societies. There is a special relation between the conch (shankha) and Shiva as is evident from the similarity between the word Shankha and the word Shankara which is one of Shiva's many names. The word Shankara could have been derived from Shankha-kara which roughly means conch-blower (Shankha = conch, Kara = blower).
In Vishnu’s lower right hand, which represents the revolving or creative tendency, I hold the conch, symbol of the five elements. The Conch (SHANKH) named PANCHJANYA is the fountain that evolves the five elements, i.e., water, fire, air, earth and sky or space. When blown it produces a sound that is associated with primeval sound from which creation developed. This is one of the most important emblems of Vishnu. The blowing of the conch symbolizes the primordial creative voice and Indian mysticism links it to the sacred sound OM, which is said to be the breath of Vishnu, pervading all space. Its convolutions are variously suggested as the rising and setting sun, hence further cementing Vishnu's solar associations.
Shankh literally means ‘pacifying the inauspicious.’ In Hinduism, origin of the conch shell took place during the Samudra Manthan or churning of ocean.
The conch has the form of a multiple spiral evolving from one point into ever-increasing spheres. It thus denotes eternity, since it may go on forever
Hindu religious art often shows deities carrying a conch shell, although both the Vamavarti and Dakshinavarti Shankha are important within Sanatana Dharama. The right-handed conch, also known as the "Sri Lakshmi Conch", is held to bring abundant blessings on the possessor. The Dakshinavarti Shankha is a kind of calling card for Sri Lakshmi (or Padma), the consort of Lord Vishnu; she removes sorrows and gives intelligence, success, and worldly freedom. According to tradition, a living right-handed conch is conceptually indistinguishable from an earthly incarnation of Vishnu or Lakshmi themselves; the blessings of Lakshmi literally flow out of the remaining shell on their own
Leaving aside the mythology part, the conch shell's significance can also be corroborated by science. If you try holding a shankha near your ear, the sound of the gently humming ocean can be heard. This is actually the natural vibration or cosmic energy of the Earth which gets magnified on entering the conch shell.