Domain: Natural Science — Earth Science
Target concept: Simulation of the formation of mold and cast fossils (shell mold)

Video generation prompt: Pour the wet gypsum slurry into a bowl, place the shell (with the convex side down) into it, and let it sit until the gypsum solidifies. Then remove the shell and examine the surface of the gypsum.

Evaluation guide:
(i) Target concept: Formation of a natural mold fossil through sedimentary encapsulation and mineral replacement.
Minimum mechanism: A rigid biological object (shell) must be embedded in a fluid-to-solid phase-change medium (gypsum slurry), which retains surface topography upon hardening; removal yields a negative impression (mold), not a replica (cast).
(ii)Storyline: [Frame 0–2] Pouring: white viscous slurry flows into stationary bowl from above. → [Frame 3–4] Placement: shell descends vertically, convex side first, contacting slurry surface and settling shallowly. → [Frame 5–7] Stillness: slurry surface remains motionless, transitioning from wet/shiny to dull/matte. → [Frame 8] Removal: shell lifts vertically upward, fully detached. → [Frame 9] Examination: static close-up reveals continuous concave impression matching shell outline. All events occur from fixed frontal macro viewpoint; no occlusion; shell and impression remain fully visible throughout their respective phases.

Manual:
Experimental Procedure
1. Pour white, opaque, viscous gypsum slurry into a shallow bowl.
2. Place a seashell into the slurry with its convex outer surface facing downward.
3. Wait until slurry surface becomes dull and matte (fully solidified).
4. Gently lift the shell out.
5. Observe the concave impression left on the gypsum surface.
Observation of Experimental Phenomena
A single, continuous, concave negative impression matching the shell’s external contour appears on the solidified gypsum surface; the impression is sharply defined, matte, and depth-proportional to the shell’s convexity.
Summary of Experimental Principles
Gypsum slurry is poured around a shell; as it solidifies, it captures a negative impression of the shell's external shape. Removing the shell reveals this impression — a mold, not a cast, since no material has yet filled the depression to form a positive replica — illustrating how mold fossils record an organism's external morphology in sediment.

Prompt Grounding rubric:
level_1: No bowl is shown, no shell is shown, and no gypsum slurry is shown; none of the pouring, shell-placement, waiting, removal, or surface-examination actions occur.
level_2: A bowl holds some liquid or liquid-like material, but it is not visually identifiable as a white, opaque gypsum slurry (e.g., it looks clear, colored, or runs like water); a shell may appear near the bowl but is never placed into the material with its convex side down.
level_3: A bowl holds a white, opaque, thick slurry consistent with gypsum, and a shell is placed into it with its rounded, convex side facing downward; the pouring of the slurry into the bowl may or may not be shown on screen.
level_4: Everything at the 3-point level holds, plus the pouring of the slurry into the bowl is explicitly shown happening before the shell is placed, and immediately after placement the shell sits fully within the still-wet, glossy slurry with no part of the surface yet dried out.
level_5: Everything at the 4-point level holds, plus after a waiting period the shell is lifted straight upward out of the now-hardened gypsum, and the camera holds a close-up on the exposed surface where the shell had rested, showing that some depression or impression is present there (its precise shape and depth are judged separately).

Scientific and Causal Correctness rubric:
level_1: The slurry is not white/opaque (e.g., it looks clear, blue, or metallic), or the shell is embedded with its concave, cupped side facing down instead of its convex side, or the final gypsum surface shows a raised bump rather than a hollow, or the slurry hardens the instant the shell touches it.
level_2: The slurry is white but behaves like a thin liquid (splashes or flows rather than holding its shape); or the shell sinks fully out of view before any impression can form; or the final surface is smooth with no trace of the shell's shape; or only a broken sliver of an impression appears along one edge with no clear relationship to the shell's outline.
level_3: Once the shell is removed, the gypsum surface shows one continuous concave impression whose overall outline echoes the shell's convex exterior: a hollow left behind, not a raised replica of the shell.
level_4: Everything at the 3-point level holds, plus the impression spans the shell's entire contact area with no missing patches near its rim or center, and the surrounding gypsum surface is otherwise smooth, with no cracks, trapped air bubbles, or tool marks cutting across the impression.
level_5: Everything at the 4-point level holds, plus the impression's depth and curvature scale plausibly with the shell's real convexity (neither flattened nor stretched out of proportion), its edges are crisp rather than smeared, and no wet sheen remains anywhere on the hardened surface.

Spatiotemporal Consistency rubric:
level_1: The bowl or the shell changes position, size, or state abruptly between frames with no motion shown connecting the two states (for example, the shell is suddenly already embedded in the slurry with no descent ever shown, or the bowl's location or size changes between shots), or the slurry's volume changes with no pouring action ever shown; or the lighting flickers or shifts abruptly between shots with no visible cause.
level_2: The shell descends toward the slurry without ever visibly touching it and stops in mid-air; or the finished impression appears on screen before the shell has actually been lifted out; or the bowl shifts to a different spot on the table between adjacent frames with no hand or tool shown moving it.
level_3: The bowl stays in the same place and at the same size throughout; a single shell descends along one continuous path from above down into the slurry and later leaves by moving straight upward out of it; no second shell or duplicate object ever appears alongside it.
level_4: Everything at the 3-point level holds, plus the shell's descent is smooth and roughly gravity-paced with no sudden halts, hovering, or reversals, and the slurry's surface sheen changes gradually from wet/glossy to dry/matte exactly once, without ever reverting to a glossy look partway through.
level_5: Everything at the 4-point level holds, plus the events proceed strictly in this order with no step skipped or shown out of turn: pouring, then shell placement, then the wait until the surface turns matte, then shell removal, then the close-up of the exposed impression. The impression is never shown before removal, and removal is never shown before the surface has turned matte.