Movie 2.

Demonstrating the LSI method using natural sand within a quasi-2D setup: 5-minute recording of the backscattered speckle pattern and side particle movement induced by a worker adult ant buried under 1, 3, and 5 cm of dry sand in a quasi-2D container (5 × 6 × 0.5 cm³). Plots depict mean absolute pixel intensity change over time, detonated as <|dI/dt|>, with blue/orange correspond to the presence/absence of the buried ant.