Gearmo

The Gearmos are race of robots encountered by the Mario brothers on a few occasions. Their origin is unknown, but they were likely created by some unknown lifeforms for manual labor.

Biology
"Biology" is a bit more loosely defined here than most cases, but these machines do consider themselves an honest to goodness species.

Appearance
Gearmos are stocky robots with a large cog in their head which pops out if Mario or Luigi jump on top of them. They have been seen moving without the cog which indicates that the cog serves no real purpose. They have pincers, wheels instead of legs and they vary in colour.

Powers and Abilities
Gearmos have the ability to rotate their head, clockwise.

Gearmos also have super strength as they are able to destroy a Chomp with their bare hands.

Reproduction
Their method of reproduction is most likely being built in factories, since they clearly lack reproductive organs, they're robots.

Diet
According to some Gearmos, they find purple coins delicious. Implying that they use this as a fuel source, or they're simply coin-operated, with the "mouths" actually being the coin slots.

Society
Gearmos often appear maintaining other galaxies. It's unknown who (or what) they work for though, or even if they have a hierarchy. They seem to have no system of government either, or perhaps they're an autonomous collective.