It may be a plate coral, they grow from stems attached to rocks spot feed it like polyps, if it either or they both need to be spot fed. I have one that came attached to a mushroom rock that the LFS thought it was a anemone, so I fed it like one. One day while cleaning the glass I hit it and it popped off (thought I killed it) but not only did it live but another one started to grow from the same spot. To date 8 have grown and the single spot is now producing 2 more. Enjoy