I've been thinking more and more about the devil fruits and have come to some conlusions about thier nature.
Nature being that they are alive. Before you go " well duh" on me hear me out.
When ever someone talks about the devil fruit they usually treat it as simply and item that can grant great power at the cost of being able to swim but all fruits exist for one reason to deliver seeds to new places.
So here we go my idea on the lifecycle of the devil fruit.
The plant that produces the devil fruit(be it bush vine or tree) does so to lure an animal (say a pirate) to swallow tha seeds and carry them to other places.It is documented by luffy that unlike most fruits the devil fruit doesn't taste very good so it goes to reason that the powers they grant are the lure to get animals to eat them. The seeds are most likey indegestable and stay the stomach or intestine for a lifetime.
As they are most common on and those who eat them seem to flock to the grandline this must be the best place for them to grow.
Why is a devil fruit user a hammer in the water?
Because only at the bottom of the sea (where their is most likely lots of seastone)can the seeds finally germinate. The animals body is then used as fertilizer.
After an unknown amount of the plant reaches the surface and starts to produce fruit. Then the cycle begins again.
Don't be suprised if a devil fruit grove is also a pirates graveyard.
Of course this could all be just a load of bull but I think it realy makes sense.
If anyone already posted and idea similar to this I had know idea and I am sorry.