The 3 eyes of coconut reperesents Lord shiva.The black shell represents Lord Karthikeya,white coconut inside represent Ma gauri and inside water represent Ma Ganga.
The mirackle of coconut is whenever it falls on ground it never falls on any ones head even a person is standing under coconut tree. Very rarely if it falls on any ones head also its said that he is going to live long life more than 100 years.
Lord Shiv and Ganesha story
One day as a child when lord Ganesha was playing he was attracted by his fathers third eye and he went to touch it. Lord Shiv stoed him and said I am going to give you a special ball to play and thhus coconut came on earth which also has 3 eyes. So coconut is very special to Lord Ganesha and coconut is offered to him.
Next, the breaking of coconut symbolizes the breaking of the ego. The coconut represents the human body and before the Lord it is shattered – breaking the ‘aham’ or ego and symbolically total surrendering and merging with the Brahman – supreme soul.
Coconut is also an important aspect in Kalasha or Poorna Kumba. Apart from this there are numerous other symbolic meaning to the coconut. Most of them revolve around its appearance like the three eyes on the coconut represent the three eyes of Lord Shiva.