We see this doughnut-shaped nebula from the side making it appear rectangular rather than round like many other planetary nebulae. A network of dense tendrils of cooler gas surround the nebula. These tendrils show up as a dark web of stripes in front of the glowing gas. Each thin dark line is many times as wide as our entire solar system!
Credit: NASA/Hubble Heritage Team (STScI/AURA)