I dont think its a purple monster. Just from what I notice from the LE purple monster, the colony is a bunch of "christmas" tree like groupings. The tips of the coral are bulbous and taper (Almost a triangular growth) And the coralites from which the polyp extend are very tiny in the LE PM. the polyp coralites in yours are more indented and "cratered." What really distinguishes you're from the LE PM is the coral tip. It's an even cylindrical growth, I dont see any tapering.
<img src="http://www.dynamicecomorphology.com/purplemonster1.gif">
Of course I could be wrong, just sharing what I notice. Your colony had me second guessing for a moment. trueblackpercula has more experience in IDing corals