Tentatively identifed as Acropora spathulata by Dr Zoe Richards who notes, "Hard to judge branch size from photo - some look quite robust (>2cm wide). If they are that wide, then the branch spacing, corallites and colour match Acropora spathulata - otherwise it is Acropora millepora." At Big Vicki's Reef, Lizard island.
© Lyle Vail