Yep, the corals will close up after lights out for the most part, I have some that stay open a bit even after lights are out. And yep, looks like an aiptasia anemone from what I can tell. I tried peppermints in my one tank and had no luck. :-( I did have luck with injecting them with a kalkewasser paste though. Gotta inject right into the mouth or you won't kill it.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.