I have a theory (which absolutely nothing to back it up) that this continues on and on, i.e. things are comprised of smaller things and (if you had the technical ability) you can always drill down another level.According to the galactical model, particles such as electrons, quarks, and gluons possess a structure; they are composed of vast numbers -quadrillions - of smaller particles on the order of 10⁻³⁵ m in size. Furthermore, according to the cosmical model - an extension of the galactical model - these smaller constituent particles are themselves composed of quadrillions of even smaller particles, on the order of 10⁻⁵⁰ m in size.