UFO

UFOs or Flying Saucers are the basic means of transportation for aliens. UFOs are high-tech vehicles that can travel large distances in space. There are also many different kinds and shapes some look like saucers (hence the name) and others look like squares.

The Shroobs use UFOs in an attempt to take over the peaceful mushroom kingdom. In their ship they abduct citizens with a strange light. The Shroobs and their UFOs appear in Mario and Luigi: Partners in Time. The mothership in the game is the last place you go. In there you destroy not just Princess Shroob but also Elder Princess Shroob. During the game you search for the Cobalt Star pieces which, Mario and Luigi didn't know until it's too late, it, when it's all put all together, releases the trapped Elder Princess Shroob.

Trivia

 * UFO is an acronym for Unidentified Flying Object.