Oniric Construct

An extremely simple Somnic creature can sometimes bind to a discarded machine, and thus gather enough substance to cross the veil and wander into the Material Plane; sadly, these creatures can be quite dangerous, as the confusion and panic they experience during and after the crossing causes them to behave erratically, waving around what are quite often several dozens of kilograms of pointy metal.

Putting them down before they can hurt you (or anyone else really) is often the best course of action.