Most of these have relaxed substantially over time, and it was only after modeling of the expected shapes of old cryovolcanoes that they were identified. It has been calculated that Ceres averages one such cryovolcano every 50 million years.[1] Yamor Mons (previously named Ysolo Mons), near the north pole, has a diameter of 16 km[20] and is the only other Cererian with the shape of Ahuna Mons,, though old and battered, the cold temperatures at the pole have preserved its shape.[17] Liberalia Mons is near the equator and has a diameter of 90 km.[21]