Where
The red warratah anemone — Actinia tenebrosa Farquhar, 1898 is found throughout New Zealand and southern Australia.  A mid-high tidal anemone, which lives on shady rock faces.

Identifying features
A medium-sized (~30 mm across when extended) red anemone with lighter red tentacles. Usually seen as a small dark red to also most black blob on the underside of rock faces—they’re usually seen unopened.

Similar to
The red colour is distinctive, so you’re unlikely to mistake this anemone for anything else.

Differs
Olive anemones are of a similar size, but are green and can live lower on the shore and in direct sunlight. Mudflat anemones can also live high on the shore, but are also brownish grey and can also live in direct sunlight.

Ecology
Red waratah anemones are interesting, as they have a very high tolerance for environmental conditions. For example, in western Australia they have been reported as surviving periods of extremely high temperatures, they also have the ability to live much lower on the shore. However, they appear to be eaten if they do. In New Zealand this anemone can be eaten by the sea-slug Pleurobranchaea maculata if it gets too low on the shore. Therefore the distribution of red warratah anemones appears to be controlled by biological factors, not physical ones.

Juveniles also have a hard time, as they can be run-over and squashed by coat-of-mail shells (chitons) and limpets, in addition to being eaten by snails (Haustrum haustorium). They are opportunistic feeders (this means they’ll try to eat pretty much anything) and have been reported to eat insects that had the misfortune to fall into the water near them.