Coconut trees are known to bear "alien mutant" coconuts. They contain much more flesh, and almost no liquid coconut water. Instead, it contains a gelatinous gel-like substance, and the coconut meat is only loosely adhered to the hard kernel.
These "mutant coconuts" are called macapuno in Tagalog and they are a delicacy. (The regular coconuts are called niyog.)
It's easy enough to figure out which coconuts are macapuno by tapping them since they have a markedly different density structure and will "sound" different.
Once a coconut tree bears a macapuno, it will continue to bear some fraction of its fruits in that form.
Human ingenuity being what it is, we can now breed trees that will yield these alien coconuts with 80% probability.
The flesh is "meatier", "stringier" and tastes quite different from regular coconuts. It's frequently used in desserts by boiling them in sugar syrup.