orcus

https://en.wikipedia.org/wiki/90482_Orcus
90482 Orcus is a Kuiper belt object with a large moon, Vanth. It was discovered on February 17, 2004 by Michael Brown, Chad Trujillo, and David Rabinowitz. It is probably a dwarf planet.

Orcus is a plutino, locked in a 2:3 resonance with Neptune, making two revolutions around the Sun to every three of Neptune's. This is much like Pluto, except that it is constrained to always be in the opposite phase of its orbit from Pluto. Because of these similarities and contrasts Orcus has been regarded as the anti-Pluto. This was a major consideration in selecting its name, as the deity Orcus was the Etruscan equivalent of the Roman Pluto, and later became an alternate name for Pluto.

The surface of Orcus is relatively bright with albedo reaching 30%, grey in color and water-rich. The ice is predominantly in crystalline form, which may be related to past cryovolcanic activity. Other compounds like methane or ammonia may also be present.