Silithium

Silithium is a material found in the cores of some comets. Silithium is highly reactive with verteron particles.

One such silithium-based comet was observed passing by the Gamma Quadrant terminus of the Bajoran Wormhole. The comet was drawn towards the wormhole, an event which was taken as proof, by some, of Trakor's Third Prophecy. The comet's silithium trail created a subspace filament within the wormhole, allowing it to be used for subspace communications without the need to open the wormhole completely. (DS9: "Destiny")