Saltwater Aquarium Fish for Marine Aquariums: Spiny Box Puffer
maybe your talking about a Spiny box puffer?
If so these guys get pretty big, I've seen one at almost 12 inches, and as with a lot of puffers they are likely to nom at the coral. I tried having a few different pieces of coral in my tank and my stars and strips puffer ate them up without hesitation. They are a beautiful and personable fish, although I've had trouble with puffers of this sort, all mine have had parasites
But they are super cool, just probably for a bit bigger of a tank, and fish only. Hope that helps!