Polycyclic Aromatic Hydrocarbons

They're actually two cones jetting out from a binary star system, at an angle where we see the discs of the base of the cone edge-on (from an angle where the disk that forms the base of a cone would look like a line).

Think of like a wine glass, where you see clearly right through the part closest to you (normal / perpendicular to you) where you're only looking through the thinnest amount of glass, but cannot see through the sides/edges of the wine glass because you're looking through more glass with more "effective" thickness.

Those edges of the cone (from our perspective) create the bright "X" (the sides of the 2 wine glasses). Then some of this X is filled with dust (brighter) and that shows the rest of the cone (the front/back of the 2 wine glasses) and some of the X is not filled with dust (darker) (no cone at all there).

The effect is enhanced by a series of straight parallel lines connecting parts of the "X". This is caused by periodic bursts of emissions, so basically those are disks viewed edge-on from our angle. Geometrically, they'd form the "base" of cones of ever-increasing size.

https://www.skyatnightmagazine.com/space-science/red-rectang...

https://esahubble.org/news/heic0408/

https://www.astronomy.com/observing/weird-object-red-rectang...