Axial filaments are otherwise known as periplasmic flagella. They are not shaped anything like regular flagella, and they provide less motility. They are called "periplasmic", because the flagella itself is located in the periplasmic space (the space between the cell membrane and cell wall). This type of flagella causes the bacteria to "wiggle", hence why the motility is less efficient than the propellor motion of regular flagella. Axial filaments are generally seen in the spirochetes.