Residue of Usability is a computer monitor in which an interface has been engraved into the glass of the monitor.
The second layer is a cloud of mouse-pointers that try to cross the engraved lines; but they bounce off because the lines stop them. The mice behave like a beeswarm flying over a rotting corpse which is the engraved interface.
The result is a collision between the virtual and the physical worlds.
By the prolific and talented Harm van den Dorpel.