Many ancient civilisations, like the Romans and Egyptians, considered mushrooms to be “the food of the gods,” due to their health benefits (and hallucinatory properties). To some, fungi are associated with death and decay, given their ability to recycle waste matter, and are often overlooked or disregarded as a result. However, the relationship between man and mushrooms remains borderline divine. They support countless ecosystems, form the bedrock of culinary traditions around the world, and much more. Mycelium, the root-like structure of fungi, has become a subject of particular interest in recent years. In life, it behaves like an air filtration sheet by metabolising pollutants; in death, its unique physical structure offers an all-natural alternative to single-use plastics. Celia attempts to resolve the entirety of the mycelium’s life cycle in a distinct tabletop air filter. Constructed out of recycled dead mycelium, it houses living mycelium taken from the common oyster mushroom (Pleurotus ostreatus) on a yarn cone, which cleanses the air of pollutants. To ensure proper functionality, the filter must be maintained through active user participation, a reflection of the symbiosis between man and mushroom. After growing the mycelium on its yarn cone, the user must mist it regularly and harvest the occasional fruiting body. Once the mycelium is spent, it is exchanged with a new generation of mycelium, with the spent material recycled into 3D-printable matter used to create new objects, including new air filters. In this way, Celia is a living, breathing vision of a circular economy. This project heralds a new generation of organic, low-tech products, facilitated by human input and enabled by natural processes. By challenging conventional narratives of quick fixes and single-use disposability, Celia deepens our understanding and appreciation of the fungal world, while simultaneously renewing our relationship to it.