Arquillian

Arquillians are a small sapient alien species from the planet Arquillia.

Overview
Arquillians are a small species. They wear a Human-sized mechanical suit (like Doctor Who's Daleks), which is used for both protection and locomotion (also hiding their true form). They are firendly but much of their energy goes to "drive" the mechanical humansuit, but they have a "autopilot" mode for making their life easier. To get the human suite to work, they have to download software programs to the brain. Too much information and the computer will have a meltdown, resulting in divulging their true identity. They also posses a powerful weapon.

In the movie the MiB need to find the galaxy and return it to the Arquillians, who are threatening to annihilate earth if it is not returned within a certain time period

Trivia

 * A member of the Arqullian Royal Family was killed on Earth, resulting in its near destruction.