Dark nebulae -- 2 kinds
It seems to me that dark nebulae are showing up in two different ways. One is as the crisp-edged but otherwise irregular dark patch that obscures the starfield behind it -- appearing 2 dimensional from our point of view, more like a splash of black paint than an object. The other is as a lump of dark, nonreflecting and nonluminous material in a sphere or oblate spheroid, which we see as having a distinct effect on the starfield around it -- as if it were crowding the stars out of its way and ending up covered or encircled by them. This is the kind I think I see involved in the large stars that come with artifacts/spikes/rays/whatever. The lumpy nebulae have a solid look to them, based on the effect they appear to have on the other matter present. I've been marking both as dark nebulae, but I will try adding a keyword #lumpnebula when I'm trying to point them out.