Looks more like cam chain tensioner pad bits which do turn an orange like color. But not completely certain as the shape differs in that I see radius instead of squared in the areas circled.
Cheers for the reply and the photos.
Huh. That is pretty frightening to think about, although I've never heard the slightest rattle from the cam chain in my half a year of driving the car, neither on a hot or a cold engine. And I am pretty paranoid about the stuff so I would've definitely noticed if there was any.
I'm guessing the cam chain tensioner was replaced after it failed by a previous owner (and scratches near the balance shaft sprocket on the oil pump prove it's had low oil pressure in the past). They probably missed a piece. The plastic piece must've been lodged somewhere and over my 5000km, got shaken lose and flowed down into the sump.
I find it odd that there's only one piece. I would assume if it has fragmented currently there would be lots of different plastic pieces.
I found random stuff in the sump the first time I dropped it, like 1cm of insulated electrical wire, a 1cm metal shard and broken up pieces of the pump chain cover, and an oil pump bolt, so I wouldn't be too surprised if this is just another well-timed gift from the previous owners
