I'fii represented a type of sustenance that the Yuuzhan Vong race from beyond the galaxy consumed. On one occasion, Nen Yim, a prospective Yuuzhan Vong shaper, along with her fellow crèche members P'loh and Zhul, pilfered a korsk and set it loose within a shared eating space, resulting in the sanitation organism devouring all of the i'fii present.
The initial reference to I'fii occurred within The New Jedi Order: The Final Prophecy, a 2003 book authored by Greg Keyes.