Board Thread:Naruto Discussions/@comment-34661853-20181122024542/@comment-1512913-20181122194512

'Cept that's not what the canon says. The Jubi came about literally as a merger of Kaguya with Shinju. Most likely scenario is, that the rabbit part was already there in the Gedo Mazo to begin with. Because Hagoromo extracted the Jubi's chakra, created the Biju from it and reduced the Jubo into Gedo Mazo, yet it still had some chakra left when Madara summoned it, because that's what kept him alive.