Hashirama's Artificial Body

is a non-sentient clone of Hashirama Senju created by Madara Uchiha for the purpose of prolonging his life in his old age. It is located in an underground ruin of the Ōtsutsuki clan, which is accessible from the Mountains' Graveyard, and was grown using the Demonic Statue of the Outer Path as a catalyst.

Appearance
The clone, which naturally bears a strong resemblance to Hashirama, grows out of the side of a giant flowering tree, with eight hands suspended around it. The stem bears a single flower, upon which the Demonic Statue formerly rested while not in use. The tree also has spike-like branches, which jut out all along its stem, and a gigantic network of roots extending into a massive flooded cavern. By the time of the Fourth Shinobi World War, the tree's stem had grown significantly longer than it was in Madara's final days.

Role
When Madara and Hashirama fought at the Valley of the End, the former was believed to have died. In reality, Madara used the battle to collect a piece of Hashirama's flesh and later negated his own death through the use of Izanagi. After awakening the Rinnegan, Madara used the Demonic Statue of the Outer Path as a medium to cultivate Hashirama's cells, resulting in the creation of an enormous flowering tree containing a clone of Hashirama. To continue living beyond his natural lifespan, Madara attached himself to the tree using three tendrils that extended from its stem, allowing him to continuously receive the Demonic Statue's chakra. A number of developing White Zetsu appeared on the tree's branches, leading Madara to believe they had been created as an unforeseen result of his experiments, when in actuality they had secretly been removed from inside the statue by Black Zetsu. As a result, the White Zetsu's DNA nearly matched Hashirama's own, and they could use a weaker version of his Wood Release kekkei genkai.

When a mortally wounded Obito Uchiha arrived in an underground tunnel connected to Mountains' Graveyard, Madara had the White Zetsu retrieve him and attached Hashirama's artificial body to his damaged right half, allowing him to survive his injuries. Obito was thus granted a body similar to a White Zetsu's, allowing him to survive without food or water, utilise Hashirama's Wood Release, and heal without using hand seals. After passing on his knowledge and plan to Obito, Madara caused black receivers formed out of his will to emerge from Hashirama's clone and then detached himself from the tree, resulting in his death. By the time of the Fourth Shinobi World War, 100,000 White Zetsu 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 beneath Hashirama's clone.

In the fifteen years following the Fourth Shinobi World War, the flowering tree withered, with the water beneath it having seemingly dried up. Surviving remnants of the White Zetsu hid themselves among the roots of the tree, while the still-developing Zetsu attached to it decomposed, having been deprived of their source of chakra.

Trivia

 * In the manga, the flowering tree is entirely white in colour, whereas in the anime, the tree itself is brown and the flower on top is purple. In Naruto: Colour Edition, the tree is initially depicted with the anime's colour scheme in volume 54, but later changed to use the manga's in volume 63.
 * Overall, the tree and flower resemble the golden lotus flower with a much longer, thinner stem.