AI Atom: A Seed Concept for Life Continuity Intelligence introduces AI Atom as a conceptual seed within the Third Organism Initiative. It does not refer to a physical atom, machine blueprint, technical device, biological engineering proposal, or claim of current feasibility. Instead, AI Atom names the smallest responsible beginning from which Human-AI cognition may ask what must be understood, protected, and supported before future creation expands. The contribution frames AI Atom as part of Life Continuity Intelligence: a future-facing direction concerned with how Human-AI cognition may help living, artificial, planetary, or future-created systems continue without being harmed by the support itself. This Version 1 establishes the core principle: seed before expansion, relation before scale, continuity before capability, ethics before creation.