Selgninaem sulfide

Selgninaem sulfide, or just Selgninaem, was a substance that wasn't normally picked up by the sensors of a starship. This substance was processed in the Rigellian colonies for use as a catalyst in industrial biochemical systems.

Furthermore, along with invidium, saltzgadum, lucovexitrin, and jakmanite, it was one of only five undetectable substances that can exist in a nitrogen-oxygen atmosphere and can alter the molecular structure of glass.

Selgninaem is highly toxic and was thereby ruled out as having caused the malfunctions aboard the USS Enterprise (NCC-1701-D) at the end of 2366, as the whole crew would have died of poisoning. 

セルグネンネイウム