Shroob UFOs, also known as ShroobFOs are the Shroobs' alien spaceships that they use for travel from place to place in Mario & Luigi: Partners in Time. These spaceships are small, but they can shoot powerful energy bolts that can turn people into Shroob Mushrooms, as well as deal devastating damage to buildings and such.
In the Yoshi Village, the Shroobs used their Shroob UFOs to shoot and mutate Yoob, a Shroobified Yoshi.
Shroob UFOS are powered by Toad energy, known as vim. The vim is sucked out of the Toads by the trees of Toadwood Forest mixed with chemicals at the Vim Factory, and afterward used as fuel for the Shroob UFOs. In the Hollijolli Village, Mario and Luigi had to fight an impossible battle that featured a Shroob UFO that counted down, when it reached 0 Mario and Luigi was defeated. The same kind of UFO appears in the 2nd half of the Elder Shrooboid battle, but could be hit with a spiked ball to reset the countdown. They were called by something that strongly resembles a Nintendo DS.