There are "normal" coconuts and there are kopyor coconuts, whose meat is not smooth and white but a bit crumbly and coarse.
How does a normal coconut become a kopyor or how do you know that a particular nut is kopyor? In Indonesia there are about one hundred species of coconut but it is not yet precisely known which variety will produce specifically kelapa kopyor nuts. A coconut palm tree with kelapa kopyor nuts will mostly continue into a kelapa kopyor-producing palm tree. But in some cases there are palm trees that produce both kelapa kopyor and normal nuts. According to coconut specialists a nut will become a kelapa kopyor if it has abnormal growth during the fruiting process. The growth is caused by a physiological change which causes genetic mutation at about six to seven months after flowering.
The villagers of Central Java have another explanation though. They say it is caused by the moon. Formerly, before the kelapa kopyor gained popularity as a delicious ingredient in drinks and sweets people considered a coconut palm tree with kelapa kopyor nuts to be a disaster. Consuming the nut was taboo. The poor nut with abnormal growth and crumbled nut meat had been devoured by the moon. Therefore many areas in Central Java called them not kelapa kopyor, but kelapa puan, meaning that the moon ate the nut meat during a lunar eclipse. To prevent that all the plants are beaten with a broom and the domestic animals are awakened so that the moon will be frightened. When eating kelapa kopyor do it on the full moon and enjoy its nutty satisfying flavour!
How to know that you have bought a kelapa kopyor? Do not shake the nut but move it from left to right. If it is heavy and feels like there are dry contents inside, it should be kelapa kopyor