hello my sense anemone has been looking very off to me. He is retracted to about the size of my palm. With greenish looking tentacles. Let me know if I should be worried or he is just expelling water of stressed.
It looks like a Sebae anemone. These creatures do strange things. They also require an established aquarium with good water quality. As stated above, check your parameters. If your water quality is good I'd just let him be for a while unless he starts showing signs like open mouth or if it starts fouling the water.