A very tiny anemone, up to 5mm tall including tentacles. Column slender, with slightly flattened, adherent base. About 16 large (bulky) non-retractile tentacles. Colour whitish or pink, very translucent. Like Protanthea simplex
, it is a very active species. It can swim by thrashing its tentacles or by 'looping' on the substrate, alternately using base and tentacles. It reproduces by transverse division, sometimes chains of up to three anemones which have not separated are found. Unlikely to be confused with any other anemones (except juvenile Protanthea simplex
) but may resemble various naked hydroids. Hydroids however are colonial animals and are attached to a substrate. Hydroids do not possess a throat, which in Gonactinia
can be seen through the transparent body wall.