Did Eris Once Hide an Ocean Beneath Its Surface?

Eris, a large Kuiper Belt object, likely once had a subsurface ocean that helped explain its current orbital state with its moon Dysnomia. Modeling by Akiba and Nimmo shows that spinning down Eris without an ocean is very difficult, while oceans appear in most successful scenarios. Though such oceans may have since frozen, insulation by porous ice, clathrates, or antifreeze like ammonia could have sustained them for billions of years.