Tritonball is a moonball of Neptuneball.
It orbits Neptuneball backwards, meaning it could've been a dwarf planet caught in Neptune's gravity (Plutoball's brother?). He misses his freedom, but being considered a moonball is a higher honor than being dwarf planetball, so he's okay. (Confirmed by Voyager 2)
Can into ice and geysers on his surface. In 3.6 billion years Triton will crash into Neptune or form a ring, making rings which cross over each other (if the other rings still exist).