Dr Andrea Crowther (SA Museum) provided the following information about Phymanthus:

"Their tentacle outgrowths are slightly different to Heteractis aurora, in that they have outgrowths that are on either side of the tentacle, not a ring like in H. aurora. The outgrowths can be from little nubbins like in your photo, to some really elaborately branched outgrowths. Here are some photos of the variety: http://www.wildsingapore.com/wildfacts/cnidaria/actiniaria/phymanthus.htm.

The two larger white tentacles are seen every now and then. Those tentacles are in line with the siphonoglyphs (grooves) in the actinopharynx (throat) – the directive axis. As per usual with sea anemones, the number of species in this genus is most likely under-represented. But because of the variation in tentacle morphology and colour, species boundaries are sketchy!"