The ruin that birthed a society; the Life and Times of a city in the throes of death.
Triastu. The City of the Three. The Hallowed City. Triastu is the holy city of Trianarianism, and is the home of the Trirex. Many have paid homage to it, and many have gone on pilgrimages to it, and have marveled in its beauty.
Sid and Jir were childhood friends growing up in the same town on the ocean. Both creative geniuses, both with the need to be better than the other. Many will tell you that this friendship created their genius while others realized, in hindsight, that it spelled the lands doom.
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.