Goo-tube

It isn't really a tube but a computerized container of tiny destructors, about the size of smoke particles, that, when released, simply pull any material they encounter apart at the molecular level. Breaking down the material mechanically and chemically allows for more destructors to be replicated; often, they leave only an amorphous puddle in their wake.

The only thing stopping the destruction is a built-in artificial Hayflick Limit that, like the ones in cells, limits the number of times a destructor can replicate. This limit was passed on to each new generation until there was a last generation. No one has yet defeated the Hayflick Limit, though some have tried.