The universe has existed as a set of pristine lights, encased in a thin, ice-like layer since anybody but the creator knew of it. Those who have travelled it, or seen it, have never described it alike. The form it takes reflects the eyes deepest truths; crystalline tears, transparent flowers, many decorative creations hanging from one ever growing thread, high upward (or down?). Stardust, reflecting scattered rainbow hues, streak across the sky: memories of forgotten beings, the remnants of destroyed planes that have since never existed at all. There is no time, an equally infinite and non-existent amount of space in the Outside that allows you to peer in. It is not a physical space. There is a reflection of it into the astral sea, which goes on forever. Realms are constantly exploding into existence like stars, and burning and fading out, as the players forget they ever were there.

In the feywild, this experience is called 寳珠/宝珠, (Bǎozhū) after the flaming pearls that dragons often carry. This space is viewed as tranquil, like a nirvana that a fey may see for but a moment when at the height of their craft, though it has mostly become slang for somebody being good at something; the original history being somewhat lost.
In the Lower Planes, this experience is Aufhockeraugen (I hope Aufhocker’s eyes) and is said to be a warning, or a bad omen. A fiend may treat this like seeing a black cat, or walking under a ladder: many don’t believe in the idea, but may talk about it nonetheless.
Nobody from the current material plane has ever seen this, as the shell of the material plane is too thick for most people to travel through in modern ages, due to the Death of the Gods. It has no name.

Material Plane Ancient History.
The material plane held many gods, long ago. The Great Goddess, Lex, ruled over the plane under many younger and smaller gods. She was kind, to a fault, and lived each day peacefully. The younger gods grew tired of the simplicity of life, watching other planes grow and change and hold life. The young twin gods Avis and Cetus devised a plan with the communion to throw her out of power. The gods used their power to trick Lex, cursing her to sleep so that they may take control of the plane. In her eternal sleep, her resentment cursed them, turning Avis and Cetus into the sky and sea respectfully, while the other gods were reborn into the first few creatures of earth, which then evolved into humanity and other such. For a while, the gods were naturally revered, with humanity drifting naturally toward worship due to their past. However, as ages passed, the gods began to be forgotten, as humanity instead pushed themselves up as the highest being of the realm, causing the Decay of earth, sea and sky as the original deities grew irrelevant to life.