A Star Point from Paper Mario.
Star Points are the equivalent of experience points in Paper Mario and Paper Mario: The Thousand-Year Door. They are green orbs with yellow stars inside them that let Mario level up. They are gained from every enemy except optional bosses and enemies at or below Mario's level. Collecting 100 of them causes Mario to level up, and the player is then required to choose to raise his HP or FP amount by 5, or BP amount by 3. The harder and stronger the enemy, the more Star Points are obtained.
In Paper Mario, Mario stops gaining Star Points after reaching level 27, though the level of some enemies and most bosses exceed 27, in order to allow bosses and the Amazy Dayzee to give out large amounts of Star Points even when Mario is at high levels. Mario maxes out at 50 HP and FP and 30 BP after reaching level 27, but badges can be used to further increase Mario's FP and HP to 65.
In the sequel, Mario maxes out at level 99 instead, but enemies except Amazy Dayzee will stop giving Mario Star Points after level 37 due to having low levels. Mario's maximum HP and FP is 200 and his maximum BP is 99. Reaching level 99 is not enough to max out Mario's stats, but a shop exists to swap stat point upgrades to other stats. Mario can further upgrade HP or FP up to a maximum of 365 with badges, though maxing out HP or FP requires that all 99 badge points be used specifically to upgrade his HP or FP and nothing else. After completing a battle that would award zero Star Points from enemies, Mario gains a Star Point as a bonus for completing the battle.
Despite being strong bosses, the Shadow Queen and Bonetail are both level zero, and thus completing their battles will only reward Mario with one Star Point.