OK you have a zoa rock.
Here are the steps for acclimating the rocks when you buy them...
1. Make a container of tank water large enough to hold the zoa rock.
2. Add 6 drops of LUGOL'S iodide/iodine and 6-8 drops of Flatworm EXIT
3. Place rock in container for 20 minutes. (purchase rock and container should be at room temp)
4. Use high powered L.E.D. light to inspect rock for NUDIBRANCHS/SNAILS/CRABS
5. The predators above will be very tricky to see. You will need to check between each polyp.
6. Lastly check for white egg rings or clusters on polyp walls(sides). If you see them scrape them off!!! These eggs will hatch into new parasitic predators!!!
7. Vigourously shake rock in container water and check it again!
8. Make another solution of water and meds and dip for another 15 minutes.
9. Inspect one last time and be sure that you see nothing that can be removed.
10. Add rock to your tank.
The pic illustrates irratated zoas. Nudibranchs are the likely cause. They will match the color of the zoas and be hard to see. Remove the rock and do the dips.
Add a 6 line wrasse to the tank. It will help.
Zoas should be open all at once or else there is a problem. Keep an eye on them.
Here is a link to the predators...
http://zoaid.com/index.php?module=Gallery2&g2_itemId=384