Aviation maintenance student. Aircraft recip engines are similar to a car engine. You can tell from screw holes/lugs, as well as the different color that it's a oil area.

Also, over time the metal can magnetize under the right conditions, although all engine blocks are normally cast or molded aluminum. The main issue is there can be a sludge like buildup that can be produced over time, so anything it can grab it will. The engravings will give it a area to grab instead of settling along bottom or in oil filter.

Aviation maintenance student. Pretty much layman term can be outer casing, but mainly we call them Cowlings or Nacelles, depending on aircraft and placement. From what I'm seeing it seems engine suffered some sort of issue causing some internal cover or component to launch out, shearing them off.

Also having a bit of a laugh at all these people saying engine was on fire, when technically Jet engines are always on fire in flight, bit the flame is contained within the combustion chamber.