A class-9 nebula is a type of nebula, whose constituent compounds and elements have sensor-deceiving properties. Some class-9 nebulae also contained volatile gases.
The Tholians once attempted to collect volatile gases from a class-9 nebula in a Bussard collector for use as a weapon. (TNG eBook: A Sea of Troubles)
External link
- Class 9 nebula article at Memory Alpha, the wiki for canon Star Trek.