Flamelung

Flamelung
The flamelung is an organ firebreathing creatures possess in order to breath fire.

It is near the chest and produces a gas(called Flieragen) that goes up the throat and turns into sparks at a snap from the second row of teeth. Then the creature exhales sharply and fire comes out the mouth.

They can produce Flieragen in the flamelung on command, like spit in a mouth.