Bet you think this is a nest in an attic. It isn’t.
This was an attempt at a nest. The bird who did this never made it into the attic, but kept trying to nest in the crack in the vent above this spot. The material kept falling, and the bird kept trying, but this is just the stuff that fell.
Note the droppings in a real nest. This one was occupied. Note the egg shell fragments on either side of the pipe.