The "Plug Robonoids" are reconnaissance drones deployed from the Gem Homeworld to accomplish special missions, such as surveying foreign planets without the aid of a Warp Pad or transportation of a space vessel. Plug Robonoids first appeared in "Marble Madness", as bigger versions of the Flask Robonoids. Plug Robonoids were sent to Earth to the Kindergarten in order to monitor The Cluster under Peridot's supervision.