'Pods

From RTAW Reefpedia

Introduction

What is generally referred to as Pods by many hobbyists are in fact the beneficial copepods and amphipods. These are detrivores, and accordingly are beneficial to the tank. They also provide a food source for other things in your tank such as mandarin fish / dragonets (which live off copepods generally and are hard to get feeding off prepared foods).

The different groups of crustaceans that are grouped together as 'pods; are:

Amphipod - 'flea' or 'shrimp-like' things people often refer to as 'pods are amphipods.
Copepod - very small, almost impossible to see with the naked eye and are 'silverfish-like'
Isopod - 'slater-like', generally not good things to have in an aquarium, as they are usually carnivores, such as the cirolanid isopods
Ostracod - not a "pod" specifically, but can resemble copepods

A deep sand bed is a good breeding ground for pods, but a refugium (by nature lacking in predators) is the best place for raising such critters. Pods can come in to your tank through live rock/coral, live sand 'seeds' and even NSW changes.