Stupid Car Parts
After some curses and skinned knuckles, I was able to extract all the loose pieces from the engine compartment, and thanks to some quick Google searches, confirm my guess that what I had in my hands was the serpentine belt tensioner. (Don't get too impressed. The search term I actually used was something more like "belt spring thing" but it got the job done.)
Now, if I were building a car, and I had to design a part whose purpose is to hold a big, heavy spring compressed and twisted while the thing it's attached to spins around at about 3000 RPMs, I don't think PLASTIC would've been my first choice of material for that part! That, combined with the cheap plastic vent louvre in the heater core than wore out two years ago, really makes me wonder what Ford engineers are thinking! Yeah, metal or something would've been more expensive, but you know what? I would've been willing to pay an extra $15 or so to get parts that wouldn't break.
Yeah, granted, it did last 120,000 miles, but after seeing the little thing that broke, I'm surprised rather than impressed. Sheesh! I wonder what Honda and Toyota use....