I watched an elegance coral be fragged and a hammer would be no different. If you have a wet saw, that works best because you can add saltwater and keep it from heating up. But, if not, if you have a rotary tool like a dremel, that works too. Have a tub of sw
available to dip the coral from time to time. Then, you just cut it where you want to. You can even then trim up the bottom to clean it up if you want. It's not necessary to have a mouth on each part, it will form a new one. I hope that makes sense.