No Edges.

Twenty-four thousand of them, and not one has an edge.

Watch the well a while. Nothing holds that shape. There is no rim and no border, nothing you could lay a finger along: there is only a place where the flow slows and the particles crowd, the way water stacks behind a stone. Lift the stone and the shape is gone. It was never a shape. It was a habit.

The toggle is two basins, and switching it relocates a population. You press, and for two seconds the whole flock leans and travels, thinning here, gathering there, arriving. Starlings do this over a field at dusk in about the same span, each bird holding its spacing while the mass goes where it likes, and nobody stands in that field calling it a transition.