Hi Dang,
Here are my guesses
The first:
Acropora austera which is common with a highly variable growth form depending on water flow and usually blue. Veron pg.250.
Hi Brad,
I have the same coral in three different tanks under the same lighting but at different distances from the lights and different water flows. They look very different to the point that it is hard to believe they are from the same parent colony. Even the coloration is slightly different.