Kepler-10b, a pyrothallasic world with a mass 4 x Earth's and a temperature of 1800K
In a tight solar orbit, these extremely hot worlds are composed primarily of rock, their thin crusts riddled with tectonic activity. This activity may often be to such a degree that there are standing lakes or even oceans of magma. The surface of these worlds can be completely turned over in a matter of years. The atmospheres are thick and dense, and marked by a thick layer of super condensed volatiles produced by the geological activity.
Hot worlds which retain a deep liquid and/or supercritical water layer are known as pyrohydrothalassic worlds.