bought thinking it was a montipora

Well, there you go. I was thinking Oxypora, but I can't find the particular species I had in mind. The tag indicates it's a maricultured piece; oxyp = Oxypora, sp. = indistinct species of.

It's the same species as this guy:
Magneto Chalice Colony

That's an Echinomorpha species; similar but not the same. It'll get more polyps, but simply needs to grow to a larger size.
There are many different species of "chalice" corals; each has it's own unique traits.

 

Good Call Evo.! I was a read along, I had no real clue

 

Cheers guys although we know what it is to a degree il get a decent pic tomorrow to update this thread