The Tree of Solitude

An enormous, sphere spanning tree from which many forms of life originated in the Sphere of Life and also stands in the center of the Dreamfall.
The tendril pierced as deep as the Sphere of Life, taking root there and slowly changing the sphere around it. A place of rampant life began to take on alien and twisted forms. The Sphere of Life however is a place of unchecked natural life and that life has a momentum that the twisted spire of nether that pierced it could not match. Slowly the corrupted forms were taken back, still strange and unreal but now folded into the natural world. Incredible creatures slowly formed natural niches and lives, spreading into the sphere and adding to its overall majesty.
The last to fall to the never-ending march of life was spire itself, turning into a towering tree that pierced its way from the sphere of life through the material sphere and brushing the edge of the Sphere of Air. For a millennia this tree stood as the spheres slowly closed the wounds it had caused around it.