Looking at these forums, i become terrified of these devilish anemones

! Everywhere i turn i hear stories of troublesome anemones that never go away! I have 3 corals in my tank now, and i wanted to stock the whole thing full of coral, but suddenly i noticed that ive never had these anemones once and ive had the tank for 2 months. I dont have this juice or peppermint shrimps either. should i be afraid

... Will they rear their ugly head anytime soon?