I finally managed to remove what seemed like a stuck stem, only to find something that seems rather odd to me. It seems to me like some merger of a threadless style stem with a threaded headset.

When I got the bike, the stem seemed fused since I wasn't able to adjust the height with the bolt loosened. I did some soaking with penetrating oil and finally got some side-to-side movement. Then I gave a few light raps to the bolt, thinking I was freeing a stuck wedge.

What I found inside was a sort of wedge that doesn't look like it was intended to be removed with the stem. Making me think it's not even intended to have adjustable stem height.

So, what do I have here and if it's an atypical stem, can I replace it easily with something more typical? Or is it still usable, as is, even if I knocked the wedge further into the fork tube.

Thanks!