Use the supplied original lamp-disc-wall schematic as the first frame. Lock the camera, the yellow lamp and stand, the horizontal guide rail, and the pale wall with its two seams. Move only the original coral disc and its short attached sliding stem a small distance toward frame right along the existing rail, then stop. The disc remains suspended in front of the separate wall and does not touch or stick to it. The original single darker shadow on that wall changes continuously in response to the moving blocker and stays on the receiving wall; after the disc stops, the shadow also holds still. Keep one lamp, one coral disc and one cast shadow. Do not move the light, add another shadow, rotate the wall, make the shadow into a floating solid disc or attach it to a nonexistent floor contact. Preserve the source layout and the visible gap. This is a requested qualitative illustrated cause-and-response sequence, not a calibrated optical simulation.