It's funny. A few chapters ago i thought the pic of the hanging zetsus (especially the spiraling one) suggested that obito spent time in them as if the were like cacoons and grew the hashirama matter into him. Doesn't look so anymore. I still say it's 50/50 if zetsu matter was used to constitute obito's new body parts. Zetsu matter has an ingredient that makes it more than hashirama matter by itself. Whatever the case, his hashirama parts broke on impact. Perhaps it was incorrect to say obito had half hashirama body but really is half zetsu. It's confusing, can obito use zetsu's chakra mimic ability that hashirama was never mentioned to have used or does obito only have hashirama abilities and lack the zetsu ones. I like your explanations, zero, it's just not all adding up yet. Zetsu is a compound of things beyond just hashirama cellular base but obito displays overwhelming powerful use of mokuton at a young age, something zetsu seems incapable of doing.
I think i make things more confusing because i did not precisely ask the important question, what is different between zetsu physically and obito's hashirama body? I think there is a difference but i think most of you don't.
Here is a different question, if the gedou mazou was destroyed, would the zetsus die?