What are these plastic parts floating in coolant tank?

[mhowellaz]

2004 Boxster S, 98K miles, new to me in the last few weeks. Noticed coolant was a smidge below the min line, and I thought I had checked that before, so I dutifully pulled up the trunk carpet to inspect the tank, look for evidence of leaks on the floor, etc.

Quite clean in the floor. I don't think this tank has been leaking. The tank itself looks good, not yellowed, and shows part number 996.106.(7?)47.09, made by Geiger Technik. Pelican lists the 996.106.147.08 as the tank for this car. Perhaps it has been replaced recently?

Peeked down into the tank itself before adding a splash of distilled water, and saw a plastic part floating down there in the coolant... poked that around with a probe to see what it was... it looks just a bit too big to be able to come up and out through the filler neck... which makes me think that part was actually born there and belongs there somewhere. But it seems to be loose. And it has a friend. Both are loose, untethered, as far as I can tell. I can roll them around with a probe.

Larger floating plastic piece on right in this pic, smaller clear plastic cap-looking piece to left.

What are these? I haven't seen a new tank up close, so I don't know what's in there. Perhaps the coolant level float (if there is such a thing) has come loose? Any clues appreciated.