Hey I got a black sun coral for free that I expected to die, as part of the base had lost its colour. But to my surprise it is completely open after the lights went out (it's only two heads though. How do you get these guys to open up while the lights are on?
Keep living the good life
Keep living the good life

Now it doesn't stay open all the time as it's not the nature of the coral but it's open enough for me to Ooooo and awww about lol. Don't forget to target feed it once in a while. The more you do the faster it'll grow. Good luck and enjoy!

