God Tree

The was a tree revered in ancient times as a deity. It was said to bear a fruit of great power once in a millennium, although it was forbidden to consume the fruit. The circumstances under which the prohibition came to be aren't known. Consumption of the Shinju's fruit bestows an ability upon its consumer's body to produce chakra.

Background
Long before the founding of the hidden villages, during an era of endless wars between mankind, a princess from faraway land had come to the place of the conflict to end it. Having decided to bring peace, Kaguya Ōtsutsuki breached the prohibition and ate the forbidden fruit of the holy tree, attaining godlike powers, making herself appear as a deity to mankind of the past and be revered as such. Using her newfound power, Kaguya had brought forth peace by force, which made her to be seen as a demon by some. Sometime later by means unknown, the Shinju incarnated into Kaguya, which made her take on a form to be known as the Ten-Tails.

Personality
The Shinju is an impartial entity and was completely devoid of feelings or even ideals as it stayed neutral and almost ambivalent to the constant wars that were waged around it by mankind.

Appearance
In its original form, the Shinju is a gargantuan tree. When it was recreated by Obito, it appeared as a tall, straight trunk, on top of which was a flower bud containing the Ten-Tails' eye.

Abilities
In its altered form, the Shinju's roots are capable of extending and capturing enemies as large as tailed beasts, allowing it to absorb their chakra to the point of desimating them almost instantly. When the Shinju's bud blooms and its eye within is revealed, the Infinite Tsukuyomi can be activated. Those who are placed under said genjutsu and attached to the Shinju's roots are gradually reduced to shells of their former selves, ultimately becoming White Zetsu.

Ten-Tails Revival Arc
Whilst Naruto and Sasuke were both on opposing views: Naruto intending to remove the tailed beasts inside the Ten-Tails, and Sasuke wanting it to burn until the last cell, as the beast was consumed, the Ten-Tails removed the Amaterasu-consumed area of its body much to the shock of the young Uchiha. When Obito warped out of the other dimension heavily wounded, Madara attempted to force him to revive him, Obito resisted and used that opportunity to make himself the Ten-Tails' jinchūriki, breaking free of the barrier. Once inside Obito's body, the Ten-Tails made an attempt to consume the human before Obito asserted control over the creature. Ultimately gaining control of the beast, Obito continued to battle the Allied Shinobi Forces where he ultimately extracted the beast from his body and had it assume its true form: the Shinju. While in this form, the tree begins attacking the shinobi, its roots sapping chakra from its victims. Madara explained the origins of the tree and how it has become the Ten-Tails, and explained that once the lotus flower atop the tree opened, the Shinju's eye would be reflected on the moon and the Eye of the Moon Plan would be completed.

As Obito continued to dominate the battle, waiting for the blooming of the Shinju to be completed, the senjutsu-enhanced teamwork of Naruto and Sasuke were able to land a critical hit on Obito. This allowed Naruto, Gaara, and Killer B to latch onto the tailed beast chakra within Obito with their own tailed beast chakra. With the combined efforts of the entire Allied Forces, the tailed beasts were freed from Obito, halting the tree's development.

Infinite Tsukuyomi Arc
Later, after Madara re-captured the nine tailed beasts and sealed them back within the Demonic Statue, the Ten-Tails revived once again. Shortly thereafter, Madara summoned the beast and ultimately sealed it within himself, making him its newest jinchūriki. When Naruto used the Sage Art: Lava Release Rasenshuriken to cut down the Shinju's flower form that was left behind by Obito, a voice told Madara to absorb the falling tree, which Madara believed to be the beast's desire to unite everything into one being.

Once Madara had completed the Eye of the Moon Plan, he was promptly betrayed by Black Zetsu, who proceeded to use itself and Madara as a medium to revive Kaguya. Soon after, while absorbing chakra from Naruto and Sasuke, Black Zetsu revealed the true story behind the creation of the Ten-Tails and Kaguya's desire to reclaim all chakra for herself.

Trivia

 * literally means 'god tree', and its size and nature have connections to both the world tree and the tree of life, motifs that are present in several real-life religions and mythologies throughout the world.
 * In addition, the story of the Shinju bearing the forbidden fruit is very similar to the story of the Tree of the knowledge of good and evil in Abrahamic religions, where Adam and Eve, the first humans, ate the forbidden fruit despite being told otherwise. Ultimately, while becoming wiser, it lead to their downfall by incurring the wrath of God. For disobeying Him, He forever cursed the two and their descendants. Adam's eldest son, Cain, would murder his younger brother, Abel, in anger and jealousy following God's rejection of his offering while accepting Abel's, which alludes to the struggle between the two sons of the Sage of the Six Paths.
 * The wooden dragon-like entities at the base of the Shinju may be a reference to Nidhogg, a dragon or serpent who eternally chews the roots of Yggdrasil in Norse mythology. Likewise with the appearance of the Shinju, it is said that should Nidhogg finally be free of its entrapment underneath Yggdrasil, its appearance into the world beyond its roots are said to herald the coming of Ragnarok, the end of the world and ultimate battle of the gods.