Lungworm
this Yuuzhan Vong bio-construct was created to allow an individual to be able to breathe oxygen in a hostile environment. The worm, carried in a coil on the user's back, was connected to the mouth with a hard-shelled form of gnullith. As part of its natural metabolism, the lungworm produced breathable oxygen, which was expelled and collected in a specialized organ for passage to the gnullith.