It's turning itself inside out which is not a good sign. Do not feed it. They don't need it.
Anemones in Captive Systems by Bob Fenner
"Underfeed, underfeed, don't feed! Underfeed, underfeed, don't feed! Most losses in captive systems are the result of over-feeding.
How many more times do I feel I need to write this? Bunches! Some anemones have been kept for YEARS without any intentional external feeding.
Know your stock! Many anemones (especially larger species) are detritivorous (a polite term meaning they eat poop), planktivorous, and largely chemoautotrophic/photosynthesizing species/individuals that hobbyists try to over-stuff with meaty/prepared foods. My bid for largest cause of loss of anemones is the consequences (lack of oxygen, hydrogen and other sulfide production...) from over-feeding.
Cut it out! Within normal temperatures and other conditions, most can and do do well on weekly feedings. If you're going on vacation, leave them alone."