Although Hueco Mundo was one of the Three Realms of the Death God World, in essence, it could only be considered the space between Soul Society and the Real World.
Hollows who weren't properly guided to Rukongai ended up in Hueco Mundo, where the concentration of spirit particles far surpassed that of the Real World and Soul Society.
Whether they were Soul Reapers or Hollows, both could perform far better here.
The high concentration of spirit particles also allowed ordinary Hollows to survive simply by breathing.
But fighting among themselves and descending into chaos was simply in a Hollow's nature.
Especially now, after the Abyss had invaded, that instinct would become even more pronounced!
It seemed as though all of Hueco Mundo had received a unique blessing. Faint strands of black patterns drifted through the air.
They looked like countless pieces of burnt black paper, appearing and vanishing, gathering and scattering...
As for the evolution of Hollows, countless ordinary Hollows might devour and fuse with one another to become the most basic Menos Grande: a Gillian.
Gillian were usually enormous, like skyscrapers.
But for all their size, their spiritual pressure was diffuse. They had no self-awareness and relied solely on instinct—clumsy, lumbering brutes.
A small number of Gillian might develop their own will and become Adjuchas, the second stage of Menos Grande. Adjuchas had to keep devouring other Menos Grande to maintain their will and avoid devolving. A few among them could break through their limits and become the highest-ranking Vasto Lorde.
There were only a handful of Vasto Lorde in all of Hueco Mundo.
Hueco Mundo itself looked like a barren desert. Here and there, quartz-like pillars jutted crookedly from beneath the sand.
Those pillars were the tops of trees belonging to the Forest of Menos beneath the desert!