Algae from Aiptasia egesta are robust representations of Symbiodiniaceae in the free-living state.

Many cnidarians rely on their dinoflagellate partners from the family Symbiodiniaceae for their ecological success. Symbiotic species of Symbiodiniaceae have two distinct life stages: inside the host, , and outside the host, . Several aspects of cnidarian-algal symbiosis can be understood by comparing these two life stages.