The fluid sac was an organ that the sentient Pa'lowick species had in place of a heart. It was sometimes used in the phrase "from the bottom of my fluid sac," which was used by Pa'lowicks to emphasize sincerity.
The fluid sac was first mentioned in "Hunt for Ziro," the ninth epsiode of the canon animated series Star Wars: The Clone Wars third season. Although the subtitles for "Hunt for Ziro" spelled sac as sack, the letter k was removed from fluid sac's spelling in later sources published on StarWars.com. This article assumes that sac is the correct spelling.
The fluid sac was first mentioned in "Hunt for Ziro," the ninth epsiode of the canon animated series Star Wars: The Clone Wars third season. Although the subtitles for "Hunt for Ziro" spelled sac as sack, the letter k was removed from fluid sac's spelling in later sources published on StarWars.com. This article assumes that sac is the correct spelling.