Round stairwell portals form a vertical bead-like column through the center of the Great Race and physically pull nearby crawlers toward the next floor.
Carl's portal sense identifies the intense central light behind the starting pods as a series of eighth-floor exits. Unlike conventional stairs and doors, the round portals can be entered from any direction and are stacked above and below one another.
The glass maze is supposed to force crawlers through long paths before they can approach the exits. Once Prepotente destroys every wall, the portals' attraction pulls the entire crawler population through simultaneously.
A vertical string of brilliant round portals suspended inside a spiral of glass chambers.
The portals turn the structural collapse into immediate mass completion of the seventh floor.