Dependent on the CG & mass to vol, the cylinder/sphere is less likely to plane than the chassis (tumble maybe) and so will probably be found near heavy items from the empennage.
I don't think that mass or density play much here as do things lke drag coefficients (shape).
So to me from a shape factor, it looks like a minature engine.
At any rate it's more likely to be closer to the engines than anything else.
But since I'm not the guy looking for it, my opinon has little value
I once bought a 5 lb magnet for the sole purpose of recovering objects like this from the mud (I used to have it snapped to the underside of my "steel-case" desk and most couldn't even pull it loose.