Goombeetle

Goombots are a sub-species of Goombas that are only found in Super Mario Galaxy and its sequel Super Mario Galaxy 2. They are basically regular Goombas that wear protective helmets, which prevent them from being stomped on.

Super Mario Galaxy
To defeat them, Mario must use a Spin to flip them over and then Jump on top of them. However if they touch Mario, they are still just as deadly as their Goomba origins and will make him lose one portion of health

Super Mario Galaxy 2
The Goombots reappear in Super Mario Galaxy 2. Its appearance is similar to the previous game, only now its eyes are bright and are larger than before.

Appearance
Goombots differ from Goombas in other ways than the fact that they wear protective helmets on top of their heads. More differences include their eyes which are not white like most other Goombas' eyes but are instead yellow-colored and just visible in the darkness of the helmet. Most Goombas also have a set of pointed fangs in their mouths but since the mouths of these Goombas are impossible to see due to the darkness, it is only assumed that they do not have those trademark fangs.

Trivia

 * In the Prima Official Game Guide, Goombots are called Metallic Goombas.