The monsters appear first as childer grubs, gruesome larval creatures that wriggle on the ground. This is the only vulnerable stage of their development. To squish them is to do the world a favour.
When grubs devour the flesh of slain darkspawn, a dramatic change occurs. To a sound of tearing flesh, legs emerge. The childer can now run down its prey with startling speed.
Upon gorging itself again, the childer transforms further, developing spindly limbs tipped with spikes that skewer prey.