Coconut and Banana are the only two fruits which are considered to be the "Sacred fruits". All other fruits are tainted fruits ( partially eaten fruits), meaning other fruits have seeds and which have the capacity to reproduce !
But in the case of coconut, if you eat coconut and throw its outer shell, nothing will grow out of it. If you want to grow a coconut tree, you have to sow the entire coconut itself.
Similarly Banana. If you eat a banana and throw its out sleeves, nothing will grow out of it. Banana tree is grown on its own when a banana plant start giving fruits.
Offering of coconut and banana in temples
Our ancestors had found this reality long ago and they had made it as a system which is still followed religiously.!