During their short existence, they've helped defend Jerma's base from ster's repeated assaults and have led a counter-attack on ster's base. All known existing Darrens were killed in these conflicts.
Darrens are large, reptilo-mammalian creatures; they are half crocodile (front half of body) and half woolly mammoth (rear half).
A herd of Darrens (potentially all that had ever existed) attacking ster's creatures.
All Darrens were eliminated in the fight.