This is one of my favorite LPS corals. It is called Frogspawn - Euphyllia divisa - and can add great color to a tank. For some reason the gorgeous green frogspawn is harder to come by, as most LFS seem to sell the brown version. I've waited a long time for a green frag, and this one was recently given to me. When it grows into a huge cluster, I've seen clownfish host in it like an anemone. It does well under most lighting and needs good water parameters for continued growth.
The colors are vivid under the right lighting (20,000 Kelvin). A year later, this image was taken of the same coral.