Mekabon

Mekabons are short robots that lived in the Muda Kingdom in Super Mario Land. When Mario comes near them, their heads come off and act like a boomerang, flying at him before coming back to reattach to the main body. They are defeated through one of two ways; either he can jump on the head and body parts separately for 100 points each, or he can wait until the head reattachs itself and then stomp on the entire Mekabon to be awarded with 400 points. It is only found in World 2-2.

Super Mario Land

 * 3DS Virtual Console manual: "This robot attacks Mario with its head. Defeat it by jumping on its head."