I dont think he created Zetsu, i think Madara did. If he was created the same way Yamato was then he would be human. Seems more to me like hes made of Hashirama and Madara DNA.
I think
Zetsu=cultivated
Yamato= insertion of dna into egg
If he was cultivated he wouldnt have a humanoid form.
Are you sure, the gedo could be some advanced ninja lab.xd
In all seriousness gedo seems to be the key to a lot of the mysteries in Naruto. Its true purpose has yet to be revealed. I always thought it might be some advanced device for Izinagi since it seems to be connected to so6p, dna, replicating, and sealing biju.
If he was cultivated he wouldnt have a humanoid form.
agree am 90 percent sure tobi was made like yamato