I had the same species (Pavona Decussata) a few years ago that had taken up an entire corner of a 72 gallon tank the sweeper tentacles that thing put out were over 6 inches long! it stung just about everything in that corner of the tank.
BadxGillen- most experts say Pavona is about as autotrophic as a coral can get so there is not much point to feed them. while I have found this to be true of most species, this species does seem to indulge to a very small extent on offered foods. the trick is very very small meaty foods