Anthopleura hermaphroditica, also known as the small brown sea anemone, is a small anemone about 10 mm wide in diameter and very brown in colour.

The brownish tinge of its outer surface makes it much harder to distinguish and find unlike some of the other sea anemones.

This particular class of anemone can be seen under water as a small brown ring in soft fine sediment and slightly submerged.

The small brown anemone is distributed throughout estuaries in current-free areas.

They all usually found attached to cockles who with they form a commensal relationship as the anemone gets protection and the cockle becomes more camouflaged and so can hide better from predators such as the mud flat whelk (Cominella glandiformis) or sea gulls.