Hubert Airy, a doctor in the 1800s, drew pictures of his aura that are instantly recognizable to many migraineurs.
My auras are often made of moving, close together lines, but very rarely in a fortification pattern. Also, mine are typically in neon green or violet.
If you don’t get why auras like this are called “fortifications” (I didn’t for a long time!), check out this old map of Bremen.
The walls and defenses (“fortifications”) around old cities were built in zigzagging circles that look quite like the outer edge of this common aura.