I noticed some spots on my anemone today. I've only had him for about 6 or so weeks so I'm not sure of his behavior, symptoms when he's not feeling good.
That is a long tentacle anemone. The spots under side indicates this. It will always have those spots, that’s normal. They usually need a deep sand bed, like 4” or more deep to stay happy. It might move, if it’s not deep enough, or doesn’t get its needs met. Deep sand bed is only one need they have. You could get a deep pot and fill it with sand to accommodate this. Yours for having it 6 weeks looks pretty good from behind, front shot would be nice.
Be careful if you decide to try moving it, don’t rip the foot, almost always a death sentence with this type of anemone if it rips its foot. Looks pretty good though.