Orcus
Discovered recently in 2004, Orcus is a candidate dwarf planet that resides in the Kuiper Belt. Not much is known about the candidate, as only observations from ground-based telescopes have gathered light from the surface. Based on spectroscopic measurements of Orcus, the surface is expected to contain both water ice and methane ice, like the surface on Pluto. There is possible evidence for ammonia on the surface of Orcus as well, suggesting a cryovolcanic mechanism that once existed on the candidate, though this is unconfirmed. More information is expected to be gathered about Orcus in the future.