Attaching to the rock would suggest gigantea. Haddoni dig into the sand. However, no colored verrucae suggests haddoni, although gigantea can have faded verrucae when the anemone isn't robust. Haddoni often have a reddish colored ring around the mouth, but not always. In the last pics, the tentacles are more similar to gigantea, though haddoni can sometimes have longer tentacles like those. I'm still not 100% certain which species it is.