A duranium shadow was a type of phenomenon involved with false sensor readings of weapons. In a confrontation with three Cardassian Galor-class-ships shortly after the discovery of the Bajoran wormhole in 2369, Major Kira Nerys and Deep Space 9 used a combination of thoron fields and duranium shadows to create the appearance that the space station was bristling with armaments. (DS9: "Emissary")