If I were to frag this hammer, where would I "score" the skeleton (as KathyC posted) and snap from? Do I cut above or below the dark section. Or do I just snap it like a wishbone? :lol:
I would let THAT hammer grow until that fleshy part that connects the heads is bare skeletin (like the lower stalk on that Y).
If you're going to frag that one soon (before the flesh pulls away from the Y) then be sure to have some Lugols in solution with tank water to help it fight off any infection caused.
Then I would grab it at the lowest point on the stalk I could (which will end up ripping flesh) and make as clean a break as possible using sharp tools. A clean exacto blade laying nearby in case the flesh holds the pieces together so that you don't have to rip them to separate the heads.
Once the coral is fragged give both halves a good swish in light lugols solution (with ample tank water). Return to tank in good, but not excessive flow to aide in healing.