Do you have a frag of Zoanthids that closed up a month ago or more, and now you’re unsure if they are still alive? If there’s still polyps, closed or open, the coral is still alive. The reasons the coral closed up can vary tremendously, so finding out how to get your coral happy and healthy again is going to take some experimenting. Try moving the coral around from spot to spot, making sure to give it several days or even a couple of weeks to open up before trying a new spot. If moving the coral doesn’t work, try dipping it to remove any potential pests, improving water quality, and experiment with other variables. Keep in mind though, other corals may be negatively affected by your parameter experimentation, so be careful.