One of the favorite pastimes for fans of One Piece is to come up with theories to explain the many mysteries that author Eiichiro Oda has scattered throughout his fantastic world. One of these mysteries regards the secret of Marijoa's treasure, with one theory positing that it is actually a tree that spawns Devil Fruits.
Devil Fruits are the source of superhuman powers that many characters in the series possess, including the protagonist Luffy,. Despite having appeared in the very first chapter, Devil Fruits remain a mystery, and almost nothing is known about their origins, purpose, or the full extent of their power. The treasure of Marijoa, on the other hand, was mentioned for the first time in chapter 761 by antagonist Donquixote Doflamingo who, despite being a pirate, enjoys special privileges from the World Government because he found out about the secret national treasure. Doflamingo revealed this information (but not what the treasure actually is) to Trafalgar Law, who is in possession of a "medical" Devil Fruit that allows the owner to perform complex surgery on himself and others, including granting someone else immortality (at the expense of the fruit 's life). YouTuber Joy_Boy Theories put together this information and came up with the theory of the Devil Fruit tree.
The theory is based on Doflamingo's words and on his obsession with obtaining the Ope Ope no Mi. According to him, the treasure is something that would shake the world to its very core. "If I'd had the power of your Ope Ope no Mi in my hands that day," he says to Law, "I would have been able to use the national treasure of Marijoa to control the world itself!" Unfortunately, Law's Devil Fruit has a vast range of powers, so it is hard to understand what Doflamingo was actually referring to. According to Joy_Boy, he was talking about the "immortality operation", which would have granted Doflamingo immortality, thus allowing him to by the limitation that prevents anyone from eating more than one Devil Fruit as the result is always death (with the notable exception of the pirate Blackbeard). Doflamingo's plan would then be to eat every Devil Fruit from the tree and rule the world with overwhelming power.
This theory, however, has some weaknesses. First of all, after talking about controlling the world, Doflamingo immediately mentions the Ope Ope no Mi's ability to swap personalities. Joy_Boy explains that this power would simply allow infiltrating Marijoa more easily by implanting Doflamingo's personality inside someone less conspicuous. However, in chapter 906, Doflamingo is shown talking again of the national treasure, and immediately after readers are shown the secret king of the world, Im, entering a sealed room in the innermost past of Marijoa, where a giant straw hat is preserved. This could have two explanations. One is that Im (whose existence is unknown to the world) is the national treasure himself, and thus controlling him through the personality swap would mean controlling the world. The other is that the straw hat is the national treasure or at least something connected to it. Another theory tries to explain that, proposing that the hat belonged to an important person from the Ancient Kingdom, Joy Boy, and preserved along with it is nothing other than Joy Boy’s dead body. The manga showed the straw hat was preserved in a very cold room, a typical environment to keep a dead body from decomposing. Also, in chapter 906, Doflamingo affirms that "power degrades quickly, it rots away in no time at all."
It's possible that one of the theories could be close to the mark. After all, One Piece's creator recently revealed that he avoids watching fan theories on YouTube, because they could be totally right. Fans will just have to wait and see.
