Aggregating anemone

Zoochlorellae, a microalgae, and zooxanthellae, a dinoflagellate, live in the tissues of the aggregating anemone. These are photosynthetic organisms that provide the anemone with food in exchange for a home. The anemone will bend towards or away from the sunlight, depending on the needs of these symbionts.
When two different aggregating anemone colonies meet, they undergo a battle. Just below the tentacular collar of an aggregating anemone are non-feeding tentacles called acrorhagi that are packed with stinging cells. The anemones at the border of a colony are smaller, often unable to reproduce, but have larger acrorhagi because they are specialized for battling with rival aggregating anemones from non-clone colonies. The battle ends with a neutral zone between the 2 colonies. After a battle, injured tissues touched by acrorhagi die and eventually slough off.