This NASA NIAC-funded project investigates fungal mycelium as a self-growing construction material for lunar and Martian habitats. Instead of transporting rigid structures, lightweight shells seeded with dormant mycelia would be activated at the destination using water and feedstock, allowing habitats to grow in situ. Mycelium offers structural strength, insulation, fire resistance, and potential radiation shielding—especially when combined with regolith or melanized fungi. The concept explores self-repair, adaptability, and bioengineered enhancements, proposing a radically lightweight, regenerative alternative for space infrastructure aligned with long-duration exploration missions.