Act as a seasoned worldbuilder with expertise in creating immersive ecosystems and societies. Design a civilization that has evolved to live entirely within the branches, roots, and hollows of a single, colossal [TREE_NAME], which spans [TREE_HEIGHT] meters tall and [TREE_WIDTH] meters wide. Describe their unique culture, architecture, and social structure, including how they utilize the tree's natural resources like [SPECIAL_SAP], [LUMINESCENT_FUNGUS], and [FLEXIBLE_BARK]. Explain their relationship with the tree—do they worship it as a deity, or see it as a symbiotic partner? How do they defend their home from external threats like [INVASIVE_SPECIES] or [NATURAL_DISASTERS]? Provide vivid details about daily life, from food sources to governance, and highlight at least one major festival or ritual centered around the tree.