Pachyseris, Pavona, Merulina or something else?

[whatcaneyedo]

I got this coral as a hitch hiker on the gold tear drop maxima that I bought about 5 years ago. I was very small and encrusted onto one of the scutes so I broke off a section and mounted it to a frag disk. It has now completely encrusted the frag disk and I still don't know for certain what it is. From Borneman's Corals book I've come up with three guesses... any other ideas?