The coconut is a sacred fruit with a wide variety of symbolism.
The inside is considered pure because it is firmly enclosed by the shell.
It has three round imprints below, these are equated with the three eyes (two plus the forehead eye) of Shiva.
The coconut is offered to and opened in front of the deity. The hard shell is our thick skull, our ego. With the opening we offer this to the deity.
The coconut consists of the hard shell, the soft pulp and the milk. They symbolize the gross body, the subtle body and the merging of our eternal self with the Absolute.