The Stone of Gelel is a source of life energy contained in a mineral seen in Naruto the Movie: Legend of the Stone of Gelel.
It was first discovered long ago as a vein of ore by Temujin's ancestors. Only the royal blood of his clan could forge stones from the ore, a process performed with flesh and blood of the body. These same forgers were also the only ones capable of implanting the stones into bodies, as well as destroying them.
The entire deposit of Gelel is said to be capable of destroying half a continent. For this reason a long and costly war was fought over it, resulting in the ore being sealed away by Temujin's ancestors. In the present day, only Kahiko knows the location of the Gelel vein (ゲレルの鉱脈, Gereru no Kōmyaku), and he and his followers protect its secret.
Years after its sealing, Haido found some remnants of the stone by destroying Temujin's village. Later, he also found the Book of Gelel, which allowed him to learn how to control the power of the crystal. Haido wanted to use the Stone of Gelel to rule the world. After a brutal fight to stop Haido, the key to the Gelel's mine was accidentally destroyed, causing the vein to go berserk, threatening to destroy the continent. To prevent this, Temujin, who carried the royal blood of his clan, destroyed the stone and the entire vein of Gelel by summoning a Space–Time Hole.
The stone itself is oval-shaped and bluish-green in colour with the appearance of somewhat white bluish tentacles on the inside of it.
The Gelel stones, when embedded into a person's body, grant them incredible regenerative powers, on par with the jinchūriki of the Nine-Tailed Demon Fox, as well as seemingly halt ageing: Nerugui the ferret lived past his life expectancy and was immortal due to having a pebble of Gelel inside him.
Those who have the stones inside their bodies can manipulate Gelel energy for combat purposes. This can range from simply channelling the energy to launch against the opponent to converting it into concentrated sound blasts or electrical energy, or even casting illusions. Haido himself can blast objects without touching them. The stone's power can also allow the users to transform into a monstrous form unique to each person, increasing their strength and prowess, as demonstrated by Haido and his followers (excluding Temujin), an aspect similar to Orochimaru's Juinjutsu.
When drawing the Gelel energy from the vein itself, it granted Haido regenerative powers far more powerful than before, as he can heal twisted limbs, even his own neck, near instantly. He can also fire a deadly laser of immense power. Only when Naruto and Temujin drew power from the vein as well to form a Gelel Rasengan and shatter the stone embedded in Haido's hand were they able to kill him.