Here is an image of a Yuuzhan Vong with a gnullith connected to them. Gnulliths represented a type of biotechnological breathing apparatus utilized by the Yuuzhan Vong. Consistent with all Yuuzhan Vong technology and tools, these were living beings; essentially, they operated as an atmospheric filtration system.
The gnullith functioned as a biological respiratory mask employed by the Yuuzhan Vong, enabling the user to respire in any non-corrosive or fluid-filled setting that contained oxygen. These creatures, which physically resembled fleshy starfish, would seal themselves over the mouth of the user and insert a lengthy proboscis down the throat. This provided the host with a continuous supply of breathable air. Although somewhat uncomfortable, unlike most Yuuzhan Vong biots, gnulliths did not cause the wearer any pain. Differing from standard breath masks, gnulliths could be utilized indefinitely because they did not depend on air canisters or require replacement filters.
The Yuuzhan Vong engineered a gnullith-villip hybrid, which merged the functions 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 effectively in vacuum environments.