The fluid sac functioned as the heart for the sentient Pa'lowick species. Pa'lowicks would sometimes say "from the bottom of my fluid sac" to highlight the genuineness of their words.
The canon animated show Star Wars: The Clone Wars third season first referenced the fluid sac in the ninth episode, "Hunt for Ziro." While the subtitles in "Hunt for Ziro" originally spelled "sac" as "sack", subsequent mentions on StarWars.com used the spelling "sac". This article will use "sac" as the correct spelling.