Pipe Master

Piper (also referred to as the Pipe Master) is a metallic creature found in Mario & Luigi: Superstar Saga. He lives in the Warp Pipes of Pipe House located next to the Beanbean Castle. He gives Mario and Luigi some helpful information about Green and Yellow Warp Pipes in the Beanbean Kingdom, explaining that Green pipes are used to warp to other Green pipes elsewhere in Beanbean Kingdom, while Yellow pipes are used for travelling between seafloor or underground and surface. He is quite friendly and helpful on the exterior, but he'll mumble some annoyed comments upon leaving the brothers.

He looks like a Bullet Bill with no eyes or a frontal curve and literally lives in the pipes.