I'm sorry, what? This is almost 100% a Goniopora, both color and form give this off clearly. Galaxea has thicker tentacles that are always green, brown or gold (these are white, instantly kicking Galaxea off the list of possibilities). Galaxea also has a vey sharp, distinct skeleton that gives the coral it's common name (tooth coral). I have yet to see the skeleton ( a pic of the skeleton would be an instant identifier) but the shape of the frag give off a round shape underneath.
A pic of the coral while closed would be immensely helpful for ID but I am almost positive that it is goniopora given the shape, color and form of the tentacles.