For fungia low light and flow. Heliofungia medium light caused by a high ledge so has shifting ambient light. Low flow but not so low tentacles look limp.
That is right. Depending on your light you may still need to acclimate it or arrange it. For example i use metal halide. The bulbs are 32" from sand bed. My sand bed can keep clams but it would kill a fungia. So just sand bed is not a catch all position for low lighting.
I place many of my LPS on a flat slab rock or frag station. Buried almost all the way in sand so it is level with sand. The plate should be on a flat level surface.
I place my cycloseris in low light, low flow on the sandbed, on glass disks that I purchased from a hobby shop. They (cycloseris) seem to easily tear their undersides on the sand. Since I've placed them on the glass disks, they've healed and seem super happy. I feed them lightly every day or heavily every other day. They like to eat.
Usually what it is. The corals start to sink into the sand. Current, fish or just the daily moving the coral start the make the corals edges become buried. Which is why I use a flat rock buried. The coral will rest on the rock not actually on the sand.