Observed during evening lantern maintenance following multiple unexplained light failures throughout the lower archive. Witness reported observing an unusually tall shadow-like form at the far end of Preservation Hall Three. The figure appeared darker than surrounding darkness and exhibited movement inconsistent with ordinary shadow projection. Associated observations included rhythmic lantern dimming reported metallic dragging sounds sudden lantern extinction shelf vibration and rapid displacement of air within the corridor. Upon return at dawn no physical damage remained. However all preservation cabinet doors throughout the hall were found standing open. Artifact positions within each cabinet had changed orientation and were uniformly facing outward toward the corridor. No signs of forced entry or environmental disturbance were documented. Photographs and sketches preserved immediately following discovery. Cause remains unknown.