Refugium

An area separate from the display tank (often in a sump), that is meant to be a refuge for organisms like “pods”. Macroalgae is often found in refugiums as both a habitat for the pods and a form of nutrient export (through trimming excess growth). Refugium organisms are either not widespread in the main tank (i.e. the lack of pod predators) or are not desired as display species; although some refugiums achieve a display quality as highlight organisms like sea grasses.