Antispiral's Universe

Antispiral's Universe is an isolated universe located between the membranes of the 10th and 11th dimensions created by Antispiral upon his birth. A grotesque and vivid space, where the Anti-Spiral war lurked in. Mega galaxies that fill the heavens in very clear way with countless backdrop of jewel-like stars, like a painting of surrealism. It's a different world that humanity has never set foot on. The universe itself has become an enemy of Simon and the others, bared its fangs.

Antispiral's Universe is a brane universe (also known as bulk or hyperspace), that exists between the membranes of the 10th and 11th dimensions as an oscillating space-time, with a different set of dimensional axes, corresponding to an 11-dimensional reality; a universe that is created, occupied and fully controlled by Antispiral according to his every whim, because of its existence being tied with his own. As Antispiral is killed, so is this universe, so the energy that maintained this reality vanished.

Antispiral's Universe is often mistaken for the Super Spiral Universe, which is the realm that exists inside Tengen Toppa Gurren Lagann, so that it may exist in the first place. The misunderstanding roots from Lordgenome stating that he and Team Dai-Gurren were inside the Super Spiral Universe, which was incorrectly (but understandably) misinterpreted as the realm Tengen Toppa Gurren Lagann stood within; Antispiral's Universe.

Trivia

 * "Even if the infinite universe stands in our way!" was said by Leeron in episode 27, indicating Antispiral's Universe spreads endlessly and consisting infinite numbers of Super Spiral galaxies.

Source
Антиспиральное измерение
 * 1) Final Drill Guidebook