The term “plate corals” refers to a collection of several different corals from the family Fungiidae.  The most common varieties are Fungia, Diaseris, Cycloseris, Lithophyllon, and Heliofungia corals.  They come in a huge variety of colors.  Plate corals prefer to be placed on the bottom of the home reef aquarium in low light and medium too low water flow.  They benefit greatly from regular feedings.  You must be careful to make sure substrate doesn't cover them.