20. The Demon Leaves Footprints (Paranormal Activity)
As the activity becomes increasingly bizarre, Micah decides to cover the floor with powder in order to detect any invisible intruders in their home. The pair are then woken up in the middle of the night to see a number of very non-human footprints on their floor, and when they review the footage later, they're able to actually see the footprints being made by adjusting the video contrast. The ambiguous shape of the prints makes it all the more WTF: are they bird-like claws or something otherworldly we've never seen before?