Investigation Stone

A smooth, fist-sized stone retrieved by the Doctor to test the black pool’s unnatural properties. When tossed into the void, it produces no splash, ripples, or reflection—silently vanishing as if erased by a force beyond physical law. The Doctor’s deliberate selection of such an ordinary object underscores his urgent need to demonstrate local spacetime’s instability before catastrophe unfolds.

3 appearances

Purpose

To serve as a controlled probe of the black pool’s anomalous properties, confirming its capacity to disrupt matter-energy continuity without violent disruption.

Significance

The stone’s disappearance becomes the definitive proof of the pool’s lethal instability, confirming the Doctor’s warnings about irreversible ecological collapse and validating his demand that military forces halt their reckless energy extraction.

Appearances in the Narrative

When this object appears and how it's used

3 moments

S13E6 · Planet of Evil Part 2

Discovery of the black pools true nature

The Doctor throws a smooth stone into the black pool, observing the complete absence of splash or ripple, thus proving an unnatural void. The stone’s disappearance underscores the pool’s lethal spacetime anomaly.

Before: A harmless geological sample held in the Doctor’s hand, unremarkable in appearance

After: Vanishes silently into the pool’s oblivion

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S13E6 · Planet of Evil Part 2

Ponti falls into deadly energy pool

The stone cast into the black pool earlier serves narrative foreshadowing—its silent disappearance underscores the lethal nature unknown to the soldiers. It is not physically present during the confrontation but symbolizes the Doctor’s earlier warning that Ponti refused to heed.

Before: Retrieved by the Doctor, tossed into the black pool—disappeared silently.

After: Already lost, its absence confirming local spacetime instability to no avail.

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S13E6 · Planet of Evil Part 2

Doctor warns of planetary collapse

Used earlier by the Doctor to demonstrate the black pool’s unnatural properties, the stone vanishes without sound or ripple—its absence now is felt as an ominous precedent before Ponti meets a similar fate.

Before: Thrown into the pool and absorbed without trace.

After: Disappeared; its silent erasure underscores the pool’s lethal unpredictability.

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