That looks to be some sort of NPS coral, not an anemone at all. Super lucky find if so, if you want to keep it, then you should feed it whatever you feed you're fish, once-twice a week through a turkey baster.
Good luck and God bless!
Whatever these are my sump was full and my Copperband Butterfly made quick work of them. Had Aiptasia and Majanos as well. I think my CBB would eat any coral I put in his territory though.