100% Triangles are miners. They collect ore from asteroids and bring it to stations. Squares are traders. They take ore from stations to planets. Planets process ore (if the population is happy) and turn it into industrial/consumer goods. Planets keep some of these, and traders take the rest to nearby planets/stations based on demand. Consumer goods help a population grow, while industrial goods are used to make more ships. Fighters (stars) patrol or guard valuable planets and stations, attacking at opportune times. Civilian ships (circles) travel between colonies and keep populations happy.