The biggest thing in the asteroid belt. Ceres is the biggest thing in the asteroid belt, about a third of all its mass, and a dwarf planet: round, but too small to have cleared its orbit. Its bright spots are salt, left where briny water seeped up and dried.
Dawn’s map of the whole dwarf planet, made from orbit in 2015. Ceres is dark grey, about as dark as asphalt, so this is close to how it looks.
USGS Astrogeology, Dawn Framing Camera global mosaic, 2015, public domain.