Orcus and Charon probably melted and differentiated, considering their higher densities and spectra indicating surfaces made of relatively clean H 2 O ice. But the lower albedos and densities of Gǃkúnǁʼhòmdímà, 55637, Varda, and Salacia suggest that they never did differentiate, or if they did, it was only in their deep interiors, not a complete melting and overturning that involved the surface. Their surfaces could remain quite cold and uncompressed even as the interior becomes warm and collapses. The liberation of volatiles could further help transport heat out of their interiors, limiting the extent of their internal collapse. An object with a cold, relatively pristine surface and a partially collapsed interior should exhibit very distinctive surface geology, with abundant thrust faults indicative of the reduction in total surface area as the interior compresses and shrinks.