Even this kind of "moving" solid isn't really moving any more than photons or falling powders. It's just setting velocity to something that is typically stationary.
Real "moving solids" would equate treating masses of particles as wholes in their collision, something that's easier said than done.
Im sorry, I thought you where saying that it was impossible to do altogether, instead of just being impossible to be pressure activated. Being pressure activated was just an after thought. I diden't mean to apear to be saying that they would be nessisary to the element. @Catelite: I know they aren't "real" moving solids but they are still "like" them. Anyway, is there a way or possibility that they could be preserved as a real element?