Crynos was a planet that had huge ice water glacial activity, the planet had a average air temperature -30 degrees Celsius essentially making it a Ice World, but underneath these huge 2 km deep icecaps was cities of the Cryoian
the planet was originally an ocean planet that had very small landmasses, however a cataclysmic event caused the local star to burn at a cooler temperatures which caused most creatures to die from the colder waters, and the more cold resistant creatures evolved into walking or burrow the snow and ice. but the Cryoians did both and built their cities in the ice.
the current state of Crynos is it being a dead planet because the planet was one of the first planets that was attacked by the Voidian Empire's annihilation forces. and even 1700 years later Crynos is still hot enough to kill anything that lands on it, but except for Cryion, who stays by this destroyed planet to see it one time to flourish again.