Pods are a group of mermaids and mermen. There are a hundred mermaids in Nixie's pod and there are other pods around the world as stated by Nixie in the episode "I Don't Believe in Mermaids". The Enchantment Song is forbidden in the girls' pod. Rita Santos said that eons ago a pod/army of mermen carried the Trident in battle and behaved in a destructive manner until a mermaid from each of the 5 oceans defeated them by drawing on the powers of the oceans and locked it away in the Trident Cave