Articles and things that should be done or placed into a world.
Old cultures since the dawn of written time have seen pictures in the night sky and asked questions of them. Who they were, where did they come from, and why do they return? The earliest efforts to distinguish these nightly visitors and give them names and meanings dates back to before the Contention of Aborior. Those first observations were different than what is seen today but most still hold true to their original origins.
These are minor things that can be dropped in anywhere to add "narrative flavor", to make it more than just another road, field, forest or beach.
The Carycian calendar has been adopted by many countries since its invention by the Blue Monk, Frezzi Alberto, in the year 1. It evolved from the wonderment Alberto felt for the natural cycles and his attempts to understand and predict them.
Tobbacos, ingridients and mind altering herbs etc.
The lowly Undead cannot be a true replacement for a living well-motivated workforce. But Undead do not tire, they do not have moods (well none worth marking), they do not require pay or lunchbreaks, and can work 24/7, if properly controled. So until activists start to fight for Undead rights, they are an interesting option.
A race of beings actually IS invunerable while in adolecence. They age, but cannot be killed. A miniority of the race (1 in 20) does not become invunerable, but rather becomes immortal at some point in thier adolecence, and ceases aging while being vunerable to death in all the normal ways. Another minority (also 1 in 20) Permanatly becomes invunerable after adolecence, but ages twice as fast as the race normally does. There is no known way to test for which of the three traits an individual manifests and the three traits cannot mix, as they are tied to the same gene, as it were.