Outwardly, the Perplexahedron is a cube. Inside, the planet is a large amount of identical rooms with various death traps developed by the Spaciosapiens. These include shifting rooms, changing gravity, wind tunnels, guards, and a currently in development trap which wrinkles people’s skin, greys their hair, and weakens their bones, then kicks them out when done. However, said trap is having trouble with the “weakens their bones” part.
One of the pieces of Map of Inifity was put in it by Professor Paradox. Unlike in Earth-10, the planet was not destroyed.