Prior to Noah's flood, the cleaner fish cleaned up the scraps of coconut husk that the shark used his teeth to crack. The coconuts were from trees that grew near the water; the coconuts fell and then floated out to sea.
Next question?
You laugh, but I can think of a good half-dozen JWs who would come up with some variation of the above as an explanation.
I know a Witness (not that old) who still thinks dinosaurs were alive at the time of flood and were there to clean up dead animals.