I do not know enough about coconut tree reproduction to fill two lines, but the tree these came from is full of coconuts, the green smooth kind. If left alone, they turn brown and fall eventually. I think what I photographed is the tiny embryonic plant. Could it be that when they fall, the juice and meat from the coconuts is used to “feed the seed”?
Just an idea, likely wrong, and as I will keep picking up coconuts, seeds, and fronds that fall, I am unlikely to be the one to learn otherwise.
Thank you and to @bouteloua who linked to this good explanation from @tiwane on the Observation as well. I have removed my countervote.