Got some marshal island and it looks weird. looks like acropora. the rock looks like fingers. not alot of flat surface on top but the bottom is pretty flat.
I recently saw a friend's order of Marshall. It looked exactly as you described- like acropora. Very nice actually! It had no corraline on it but with time it will be very nice.
I got some Marshall Island rock and it is as you described. I've had it for about a month along with some florida LR. Coralline is slowly gorwing on it now. But I like it as it has a lot of caves and crevices for fish and shrimp to hide in.
Almost all Marshall Island rock has an Acropora look to it. At least all the Marshall Island rock I've ever received. Very nice rock, however it's a little expensive.