Crynos is a planet that was once a ocean world. however the Local star suffered a Cataclysmic even that ejected its internal plasma into space causing it to burn into a cooler temperature. this also drop the temperature of crynos causing many lifeforms to die from the sudden freaze over of the oceans. the creatures that did survive ended up to go under a rapid forced evolution to walk or burrow the frozen ice lands.
but one species in particular have developed high enough intelligence to start colonize the Frozen planet as they call themselves the Cryoians.