Stevensonian worlds are terrestrial in nature, and tend to vary between 0.5 and 1.5 Earth masses. They have a hot core which is still cooling, and a thick atmosphere which tends to trap the heat. Unlike Kauketean worlds though, they have cooled enough to be potentially habitable, and may have liquid water on the surface.
The habitable period doesn't last long, but a few small might actually have life. Such life rarely reaches the level of an EuGaian world, but bacteria and maybe more complicated life forms could have time to evolve before the temperature of the world plummets.
Eventually these worlds will freeze unless they find their way into a neighbouring solar system.