Like all life on Mustafar, the evolution of lava fleas began underground in the planet's few land masses that were not fissured by magma eruptions.
As larval crystalline worms, lava fleas would burrow through the dirt underground and feed on rocks, producing potent acids to break them down into digestible form. This process created complex, but fine networks of caverns into which the Mustafarians would follow. By the next year, the larvae would grow to a meter in length, and wrap itself in a chrysalis-like encasement, undergoing metamorphosis over the next month, where they would emerge as a meter-tall, six-legged lava flea.
The lava flea would then continue digesting rocks and other nutrients, shedding its protective shell with time. The native Mustafarians eventually began using these shells as armor, due to its insulation allowing them to explore the surface of the blistering hot planet. Even their eyes were protected by a nictitating membrane. Lava fleas were also very suitable and efficient mounts due to their agility and light weight, able to leap distances of up to 30 meters.
The lava fleas were of considerable benefit to the Mustafarians who were distrustful of more advanced technology in the galaxy. The creatures were easily domesticated, and were used for transport with their agility, particularly jumping ability, highly valued. Even when the Techno Union arrived on Mustafar with modern marvels such as repulsorlift travel, most Mustafarians still preferred to travel by lava fleas.
Also, in the settlement of Fralideja, there was a manhood ritual in which youth were expected to jump across the nearby lava waterfall on a lava flea, bearing no protective armor.