TI (finally) L that almost all of the areas in reborn are based off of some kind of gemstone/rock. Opal, Peridot, Obsidia, Onyx, Coral, Jasper, Beryl, Azurine, Iolite, Citrine, Ametrine, Celestine, Aventurine, Tourmaline... The list goes on. (I don't know where Byxbysion comes from, though!)