Predeluvian Sandstone of Demnos

The Doctor picks up and examines this coarse sandstone, identifying the embedded circuit of base metal fused into it—a signature of alien origin. He uses the artifact’s authenticity not to empower the ritual but to expose Hieronymous’s false validation, turning the cult’s own prophecy weapon against them.

The Doctor turns to see Sarah, leveraging the predeluvian artifact’s significance earlier mentioned to undermine Hieronymous’ authority by mocking the ritual’s credibility.

The predeluvian sandstone appears as the Doctor identifies it among Hieronymous’ arcane items, serving as tangible proof of alien interaction and disrupting the astrologer’s claim to terrestrial authority. Though unused as a weapon, its revelation undermines Hieronymous psychologically during the critical standoff.

The predeluvian sandstone shifts under the Doctor’s hands as he uncovers a glass surface embedded in the quarry floor. Sand brushes aside to reveal a flawless reflector warping into circuit patterns. The Doctor uses it to momentarily conceal the illusion mirror, but the surface’s distortions bleed crimson light and grotesque imagery aligned with the attacks.