Hashirama's Artificial Body

is a non-sentient clone of Hashirama Senju created by Madara Uchiha in order to harvest his unique Wood Release kekkei genkai. It is located in the underground section of the Mountains' Graveyard, and was grown using the Demonic Statue of the Outer Path's power as a catalyst.

Appearance
The clone, which naturally bears strong resemblance to Hashirama, grows out of the side of a giant flowering tree, with eight hands suspended around it. The white (brown in the anime) stem, which grew noticeably longer by the time Obito Uchiha showed the tree to Kabuto Yakushi, bears a single (purple in the anime) flower, upon which the Demonic Statue sat among its petals. The tree also has spike-like protrusions, which jut out from around and along the tree's stem, and a gigantic network of roots that extends into a massive flooded cavern.

Role
When Hashirama fought Madara Uchiha at the Valley of the End, Madara was believed to have been killed. However, as Obito Uchiha learned, Madara used the battle to collect Hashirama's DNA, which he later cultivated using the Demonic Statue of the Outer Path, producing a flowering tree containing a clone of Hashirama. To sustain his life in his old age, Madara continuously took in the Demonic Statue's chakra by attaching himself to the tree using three tendrils that extended from its stem. A number of developing White Zetsu were attached to the tree's "branches", having been removed from inside the statue by Black Zetsu, which lead Madara to believe they had been produced by the tree itself. Before Madara passed away, he placed some of his will into the tree, represented by the chakra receiver protruding from the Demonic Statue's navel.

By the time of the Fourth Shinobi World War, the White Zetsu (100,000 in number) had fully developed. After Kabuto Yakushi captured Yamato and used him to further improve the White Zetsu, he suspended him in the tree's stem, facing Hashirama's clone.

Trivia

 * Overall, the tree and flower resemble the golden lotus flower with a much longer, thinner stem.