A Yuuzhan Vong is shown with a gnullith attached to them. Gnulliths represented a type of biotechnological breathing apparatus utilized by the Yuuzhan Vong. Consistent with all Yuuzhan Vong tools and equipment, these were living organisms; essentially, they acted as an atmospheric filtration system.
The gnullith functioned as a biological breathing mask, employed by the Yuuzhan Vong, that enabled the user to respire in any non-caustic or liquid-based setting containing oxygen. These organisms, resembling fleshy, starfish-esque beings, would seal themselves over the mouth of the user and insert a lengthy proboscis into the throat to supply the host with breathable air. While somewhat uncomfortable during use, unlike the majority of Yuuzhan Vong biots, gnulliths did not cause pain to the wearer. In contrast to breath masks, gnulliths could be continuously utilized, as they did not rely on air canisters or necessitate replacement filters.
The Yuuzhan Vong engineered a gnullith-villip hybrid, which merged the functionalities of both a communication device and a breathing apparatus. When used in conjunction with lungworms and vacuum cloakers, the gnullith-villip hybrid allowed a Yuuzhan Vong to both breathe and communicate while in vacuum environments.