foo fighters (jojo)
A supporting character from JoJo no Kimyou na Bouken Part 6. A group of plankton given sentience by the effects of Enrico Pucci's Stand Whitesnake. The plankton possess the body of a dead female prison inmate and are capable of speech. Foo Fighters is essentially a Stand, but is described as something closer to a new species.
In her human body, Foo Fighters requires constant hydration to sustain the plankton living inside. As such, she is almost always holding a drink cup when not near a water source.
Her name is frequently shortened to just "F.F".