Was it ever said who was hanging in Szayel Aporro's lab when Mayuri opened the Door?

Cuz that scene always bothered me when I watched it and it was never explained... but has that ever been cleared up?? I always thought it was the 2 Privion Espada.. but 1 was skinny with long legs and the other was shorter and wearing a long robe of sorts.. Any Closure to this??