Not your mother's extruder! Kidding... This simple yet very effective extruder is the brainchild of some members of the QR's community (in no particular order: Shauki B. / Mauro Manco (Exilaus) / Dale Dunn / Darkberg Aryavis (Flint Eastwood) and myself). I just tried to put it in a pleasant form. The name comes from the ring that looks like an aureola and it uses the flint wheel of a lighter. It was done initially for a NEMA17 and 1.75mm filament.
The nice detail about this design is that it's almost self-locking on the filament and the forces applied on the stepper motor are cancelled by each others.