Gem Goob

Gem Goobs are rare, blue ghosts in Luigi's Mansion 3. They are gem versions of Goobs, similar to Gold Greenies from Luigi's Mansion: Dark Moon. They are found very rarely throughout The Last Resort and drop a gem if defeated. If Luigi finds one, it will panic and run around, trying to escape. If Luigi does not capture it in time, it will escape and can no longer be captured. Usually the Gem Goobs hold a clear gem, but on floors 12 and 13, the ghost holds a different gem. On floor 12, called "The Spectral Catch", a Gem Goob drops a ruby, or the red gem. On floor 13, called the "Fitness Center," there are 2 Gem Goobs: one with a diamond, or clear gem, and one with an amythest, or purple gem.

Golden Goobs, another rare variety of Goobs, also appear throughout the game, and are very similar to Gem Goobs. They also drop treasure if defeated.