A dead anemone is like a shock to your system kinda like a dead fish if your system can handle it then your all good. Try running your lights on for a longer than normal schedule to see if the anemone will come out to bask no matter where its at. Recheck the area where you anemone was last seen. For the most part they just shrink up in the same crevice where its foot was, but they will move on you to get to a spot that they like (more flow, less flow, more light, less light).