Look what I found in the oil pan... any ideas?

[elgyqc]

I am doing maintenance (cam tensioner chain pads, RMS etc.) on the spare engine that was in my 2000 Boxster 5-speed for the last couple of years.
I dropped the oil pan and found these pieces of plastic.



I can't figure out where they come from and I don't like not knowing. There are some very small pieces of the same material in the oil filter, along with chips from the tensioner pads and some bits of sealant. The engine was running fine. The plastic looks like it could be a piece of the oil pan baffle in terms of colour and thickness, but the baffle looks pristine. I don't see anything broken in the bottom of the engine and there is nothing in the area of the camshafts that could be a source. It is not the tensioner chain pads. I did not drop the oil pan before installing the engine 3 years ago so I have no idea if this dates from before or after I bought it.
Thanks in advance...