The name Nurva is derived from nerve. Since the Bawg is a giant, living organism, it may also possess nerves that allow it to sense and possibly even move. Nerves use weak electrical currents to convey signals, but the Bawg's Nurva are much bigger, and therefore the electricity that runs through them is strong enough to zap Flux as she moves between two Nurva.
Nurva can be farmed by planting a Nurva seed in some Furdle Blulch.
In the Petty Theft story, 19 Nurva seeds are grown in pre-existing patches around Chikkix's home. In Brubus culture, failing to remove Nurva from your home is seen as a sign of "disordered priorities", decreasing one's rank in the roost.