There are several Acropora species that form tables similar to those on this page, including A. clathrata, A. cytherea and A. hyacinthus. For the most part, it requires a fairly close look at the structure and orientation of the small branches to distinguish them, and most of these photos do not have sufficient detail. The distributions of all three of these species include the Marshall Islands, so it is possible that all three are represented among these photos.
Sometimes, especially when the tables get large and heavy, they may tilt or be washed over by surges. Further growth then takes place at an angle to the original growth to keep the flat growing surface of the coral facing the sunlight.
The white patches appear to be some sort of coral disease.
Like many other corals, the tables are subject to bleaching when the water gets too warm. For more information on bleaching, see this.
Created 13 December 2020