When Derek was installing our (beautiful, glorious, spectacular) new hot water heater recently, he had to pry off a metal thingy that was covering a hole in the old chimney that goes from the roof, through the center of our house, and on down to the basement. This was because he had to connect this silver tube thingy from the top of the water heater to that hole in the chimney for... ventilation? I do know we majorly sweated over whether there was the proper amount of rise- I think it was a quarter inch per foot of tubing- from the water heater to this ventilation(?) hole; our new water heater is much taller than the old one, and for a while there was some question as to whether we were going to be able to make this work. Derek's dad threw around fun words like "carbon monoxide poisoning" just to make sure we grasped how important this whole proper ventilation thing was.
After Derek opened up that hole in the chimney but before he attached the new tube thingy, we took a moment to peer into the hole. I suggested a picture be taken, but that Derek be the one to stick his hand in there to do so. There was absolutely no question whatsoever that if I were to attempt the picture taking, I would have somehow dropped my phone in the chimney, never to be retrieved.
So, yeah. Derek took the pictures.
He first took the previous one, looking down, then the next pic, looking up. Hello, 117-year-old chimney! Hello, daylight!
When I looked at this photo later, though... what the heck? What is that? That thing?
Clearly it could be any of those three things, but a word to the wise, friends: do not google "nest in chimney." Most of the results are fairly benign, but a few will serve to further your belief that Australia is not, in fact, fit for human habitation. Just trust me on this.