The most peculiar ring galaxies refuse their assigned origin story: Hoag's Object is isolated, companion-free, debris-free, with a symmetric, dynamically settled ring that looks ancient rather than transient (Hoag 1950; Finkelman 2011). Collisional ring formation demands a visible intruder, a short-lived wave, and kinematic scars, and the hardest cases show none of the three.
The model can only make a ring by hitting a disk, because morphology is assembled gradually by mergers and instabilities from featureless initial conditions. A stable, isolated, perfect ring therefore requires choreographed multi-step interactions or invisible ejected companions, scenario-building tuned case by case for objects that look like they were simply born this way.
SCT takes the morphology at face value: the ring is an initial condition, not an accident. Galaxy morphology in SCT is set at the seeding epoch by the angular momentum the formation collision deposited, the ratio of inherited J to the circular value selecting the structural type, and preserved thereafter by exact conservation (P31, P32). A seeding event with high specific angular momentum raises a centrifugal barrier that prevents matter from settling inward, condensing the gas into a circular ring around a sparse interior, with the central spheroid forming from the low-J core of the same deposit. Hoag's Object is what a high-J seeding looks like after billions of undisturbed years: no intruder, no debris, no scars, because there was no encounter, only geometry.
This is the same seeding-epoch morphology principle that carries the JWST grand-design spirals and bars at high redshift (the L-10 signature: structural type set at formation and protected by Noether's theorem), read here at its rarest setting. Polar-ring systems extend the family naturally: two J components from distinct cascade contributions, the central body holding one axis and the ring the perpendicular other, a configuration mergers must engineer but deposition simply delivers. The inheritance formalism is in Paper 5, From Chaos To Corotating Hierarchies, with the seeding mechanics in Paper 4, From Chaos To Collisothermal Cosmogenesis.
Keystone economy: P31 raises the barrier, P32 preserves the result. The rarity is just the tail of the impact-parameter distribution; the permanence is conservation law.
Deep environmental imaging carries the kill in both directions: if JWST and Euclid eventually locate the required companions, tidal debris, or kinematic scars around every isolated ring, the collisional story closes and the seeding origin is unnecessary. Conversely, SCT requires ring kinematics to be dynamically primordial: a ring whose stellar populations and velocity structure date its assembly to a recent encounter rather than to the formation epoch would refute the born-this-way reading for that object, and a census where all rings prove transient would refute it for the class.