Bones are how players keep rank and score on game modes. Bones are dropped by players who have died. If you deal damage to a player before they die, you drop a fraction (40%) of the amount of bones they had. They drop the rest of the bones. Upon death players also drop health orbs, stamina orbs, and coins. The single bones is worth 1 bone, the crossed bones are worth 2, the rib cage bone is worth 3, and the skull is worth 5.
Bones contribute to a total bone score. The total number of bones show upon the players death as part of the respawn UI, and also shows on the top 100 bone score leaderboard if the score is high enough. Bone score contributes to the bone rank, which is what is shown on the leaderboard. Total bone score is reduced 2% every day.