Cylindrons are a subatomic particle of the geometron class. When cylindrons gather in large enough quantities, they emit a gravity bending field (also known as a geometry field) in the shape of a cylinder. This geometry field will cause celestial bodies in their presence to take on a cylindrical shape. Other geometrons are speculated to exist, such as conitrons and pyramidrons, but cylindrons are the only ones which have been detected as geometrons are speculated to expel other, less numerous types of geometrons from their presence.

The presence of cylindrons and the resulting cylindrical geometry field are what causes otherworld to be cylindrical in shape. Cylindrons were first detected at the Academy of Physics in Miran, Felure. There is debate about whether spherons may exist, as while there are plenty of spherical celestial bodies visible from otherworld, spheres are the shapes that bodies would naturally take on as a result of gravity, in the absence of any geometrons.