The footy bit that holds the magnets for the bottom case also has a mystery cable locked inside it.

Closer inspection reveals: yet more mystery!The cable sports four contact points. Perhaps more testing points?

Recognizes the color of the base, so the Home can coordinate its outfits better.

Vestigial charging mechanism. (Maybe the Home's architects intended it be a portable device?)

Abandoned easter egg dungeon level for teardown engineers.