Inside the experiment
The cat is a ring of fifty-six small weights joined by springs, a soft body with no skeleton. Three forces keep it a loaf. Pressure pushes outward whenever the enclosed area shrinks, like air in a balloon. Shape matching finds the best-fit rotation of the resting loaf every step and pulls each weight gently back toward it; that is the Firmness slider. Damping bleeds away wobble relative to the body's own motion, so it still falls at full speed but settles instead of ringing forever.
The face, paws, tail and bubbles are not simulated. Each is pinned to the nearby rim with distance weights, so when the rim dents, the face dents with it.
Fold ears already lie bent forward, like little caps. Squash the loaf and they press flatter against the head; stretch it and they lift almost upright. They sit on their own springs, so they flop when the body lands.
The simulation takes eight small steps per frame, which is why a hard fling stretches the jelly without tearing it.