The spheres came in a variety of sizes, such as the relatively small orbs located within the chest cavity of the Tomb Guardians, or the larger spheres that powered Zeffonian technology within their tombs. These larger spheres, despite their size, could be easily manipulated through use of the Force.
The spheres had Zeffo writing inscribed across their diameters, and were constructed from a bronze-hued metal. The spheres could be durable, surviving for many years after the disappearance of the Zeffo, though several spheres were damaged and broken by the time that Cal Kestis discovered the Zeffo tombs. A faint rumbling could be constantly heard from within the spheres, amplified when they were moved. Some spheres consisted of several layers rotating in various directions around a central glowing blue energy core. On those without rotating portions, this blue energy could be seen emanating from their inscribed writing, and those located within Tomb Guardians were suspended inside their open chests by similar blue energy. It was possible to use the Force to temporarily remove the sphere from a Guardian, incapacitating it momentarily. So long as they were not destroyed, Zeffo energy spheres operated constantly and entirely self-sufficiently.
The smaller variety of sphere could be found powering Tomb Guardians in an ancient Zeffo temple on the planet Ontotho, as well as the Tomb of Miktrull and Tomb of Eilram on Zeffo. The larger sphere type was located in an underground area on the planet Bogano, as well as in the two tombs on Zeffo. Additionally, Jedi Master Eno Cordova used an energy sphere to power his workshop on Bogano.
Eno Cordova and his Padawan Cere Junda risked their lives to uncover the secrets of the temple on Ontotho, where they encountered the deadly energy sphere-powered Tomb Guardians.
In 14 BBY, five years after the fall of the Jedi Order, former Jedi Padawan Cal Kestis explored the Tombs of Eilram and Miktrull with the droid BD-1, encountering and using the spheres to navigate through them; he also encountered the Tomb Guardians there, which responded hostilely to his presence and used the power of their core spheres to attack him.
In the 2019 video game Star Wars Jedi: Fallen Order, energy spheres are often used as an element in puzzle rooms throughout the game. The player is typically required to manipulate the energy spheres using the Force in order to move the spheres to their objective.