Mystery Fireplace

Most houses in my neighborhood have wood-burning fireplaces. Our 1926 duplex has this old former gas unit in the upstairs apartment...and nothing downstairs (though the wood floor downstairs has inlays in the shape of a hearth at this spot, so it looks like there was once something there that has since been removed). Trying to figure out if this gas fireplace is original (or perhaps a '30s or '40s replacement for an original wood-burning fireplace)...what kind of stove/burner would have been in it...if there would have been an identical unit downstairs...etc.

 

Here's what the old gas jet looks like...

 

And here's a spot that looks like it was once burned/melted by heat from rising from some sort of stove or burner.

 

Got any ideas what kind of heat source might have been here and what it might have looked like? Since there's no vent, I'm assuming it can't be restored...but I do have a lingering fantasy that we might be able to have some sort of period-appropriate stove or fireplace here someday...