Why do Hindus worship a coconut and offer it to a deity because Formerly animal sacrifice was practiced in yajnas in India, symbolizing the offering of wealth to the devas. Slowly this practice was discontinued and the coconut, symbolizing life, came to be used instead.
A coconut is broken during worship rituals in mandirs and shrines. It is also broken on occasions like the inauguration or opening of new building, factories, roads, bridges, ships, etc. the splitting of a coconut symbolizes the shattering of one’s ego. The coconut water represents the base instincts, which is offered with the white kernel to God. It is also placed on top of kalasha and used for worship on auspicious social and religious occasions like weddings, temples consecration ceremonies, etc. finally the coconut is also offered into the sacrificial fire during a homa ceremony mainly performed by householders.
The coconut is worshiped with the kalasha because the latter symbolizes prosperity and auspiciousness.