You can't always base the identity of a coral on shape, where it has polyps or how it looks. There are so many growth variations between different corals. To Identical frags from the same parent coral can grow totally different depending on lighting water flow and so on. The best I can say is your coral looks like a colt. Second guess would be a variant of sinularia. As far as a white colt goes, I've never seen a healthy one. Its generally just a another redish colt that is lacking enough light to support the zoanthelia in their flesh for photosynthisis. Its the same scenario with the infamous white seabae anemones. If you see a healthy one you can tell that they are at least tan in color varying into more vibrant colors. I have worked with a friend of mine who owns a soft coral aquaculture facility here in ME for a few years now and out of the hundred plus species of mainly soft corals that we deal with we have never seen a white coral either stay white or stay alive. When provided with good strong lighting they either start hosting more zoanthelia and color up or they whither away and die. Either way your coral, whether its a colt or not could probably benefit from being in higher lighting and flow. Once it grows a bit more it may take on some clearer characteristics of what type it is. I still say red colt but you have to wait and see as it grows.