Like everything else on Calisto One, eras as well are connected with their relationship with Sumdrills.

Digging Era – after Schism led them to the cold inactive ground of Calisto One, Sumdrill-Units dug their way through the ground

In Air Era – after Calisto One was warmed up, they floated above in their safe Earth-Ships that were their home and observed the cooling between bounces

Hatching Era – after their domes, eggs and ground were finally cracked they left their Earth-Ships to commit to the ground of Calisto One

Expansion Era – after they set up the first cities that weren’t grounded on Earth, conquering of the new land started

Kingdom Era – the new society imitated the times of old but no one was really invested in remembering the past