The Modular People were a posthuman species of cell-colonies that evolved from the Colonials.
The core of the Modular People were a species of specialized sapient Colonials whose function was to direct other specialized Colonials. They spread across the planet and adapted other Colonial colonies to work under their control. Thus they formed the civilization of the Modular People.
Eventually, the Modular People built industrialized mega-cities. Every "individual" was a colony formed from groups of different Colonials, with each colony being designed for their purpose. Also, they could split up and form new individuals from their "cells". The only thing constant in all of their protean existence was their mental and cultural unity.
Modular People society was an utopia of equality where everybody was happy to be a part of the whole.
Over a timespan of about 80 million years, the Second Empire developed, through the combined effort of all members, into a galaxy-spanning empire, even though the members never met each other personally, and all of the species colonized other planets.
Though they were prepared to face an alien invasion, the Empire didn't think about an invasion from other posthumans, and so the Modular People, along with all of their cousins, were quickly wiped out by the Gravital as part of their interstellar conquest.
- All Tomorrows, by C. M. Koseman (2008)