The Kuiper Belt

About
The Kuiper Belt is a group of objects outside of Neptune's orbit. It contains 4 out of 5 dwarf planets, (long story), and has a lot of comets. The largest object was the former dwarf planet, Triton and now Pluto. While Triton is not a Kuiper Belt Object anymore, it was once the largest. And another moon, Nereid also could have been a Kuiper Belt Object too, because of it's strange orbit. Nereid's orbit could have been like that due to the capture of Triton though.