A Shankha (Sanskrit: शङ्ख, śaṅkha, meaning 'conch') is a conch shell that holds religious and ritual importance in Hinduism. The shankha is used as a trumpet in Hindu ritual and, in earlier times, was also used as a war trumpet.
In Hinduism, a particular shankha called Panchajanya is regarded as a sacred emblem of Vishnu, the preserver deity. The shankha is praised in Hindu scriptures as a giver of fame, longevity and prosperity, as a cleanser of sin, and as the abode of Lakshmi, the goddess of prosperity and consort of Vishnu. It is frequently depicted in Hindu art in association with Vishnu.
As a symbol of water, the shankha is also associated with female fertility and with serpents (nāgas) in traditional iconography. Beyond Hinduism, the shankha is one of the eight auspicious symbols of Buddhism, known as the Ashtamangala, where it represents the pervasive sound of the Buddhist teachings.
Adapted from the English Wikipedia article on Shankha.