[Theory] The real purpose of Zetsu.

[Danzosama]

There is one point which hasn't yet been explained in the manga and this is once the infinite Tsukuyomi takes effect how can all those Ninja be able to survive in this dream world without having food or water and everything they need to survive in the real world?. The answer is with Zetsu and his real purpose to be vessels for every ninja in some way to enable them to survive without food or water and also no need to poop. Zetsu is clearly the logical answer to this question.

 

[thegame]

It's a manga, this doesn't need to be thought through U_U

Infinite tsukuyomi could also last eternity in the mind, but few seconds real life. That would work as well..

 

[VongolaX]

He serves as a limb-replacement...

 

[Draw]

I was thinking this to. Madara says the white zetsu are a failed experiment and there is only 1 swirl zetsu maybe madara planned on making suits for everybody