Sock anemone in Port Elizabeth.
Photo Neil Bruton
Two views of another individual
Photos Johan Swanepoel
The fully revised and updated, and much thicker, "Two Oceans" has just been released, and it includes this rather odd anemone (it was not present in the previous editions). Known by various names: walking anemone (it moves around more than other anemones, and never sticks its base down like others), sock anemone (it does resemble an airport windsock) or, as in Two Oceans, hedgehog anemone (SURG prefers "sock", by the way), its known distribution is given as roughly Cape Town to Cape Agulhas. It's sighting in Port Elizabeth by two different divers shows that its range is much further east than previously known!
For more details on this species, see "A field guide to the Marine Animals of the Cape Peninsula" available directly from SURG or better dive and book stores in Cape Town.
A field guide to the Marine Animals of the Cape Peninsula, G Jones, 2008
Two Oceans, A guide to the marine life of Southern Africa, GM Branch, CL Griffiths, ML Branch and LE Beckley, revised edition 2010