so why do most of them look like water spiraling down a drain?
When two current filaments passing through plasma (at the galactic scale, these are known as “birkeland currents”) get close enough to each other, they will be attracted to each other and begin to orbit around each other, much like the stars in a binary star system orbit each other. This traps and begins to condense a volume of plasma between the orbiting currents, and this trapped plasma becomes nucleus of a new galaxy.
At the same time, the rotational movement of the filaments creates a secondary current flow axial to their motion, which pulls plasma from the surrounding area towards the nucleus. This plasma that is being pulled inward becomes the arms of the spiral galaxy. They end up looking like “water spiraling down a drain” because both the plasma and the water are rotating around a central point while at the same time being pulled toward the central point axially.