1. Materials: Sharp blade (NEW), cutting surface (a cutting board is best), water bath (keeps the slime out of your tank), and THE VICTIM. Always wear proper protective gear! Gloves...goggles... etc.
2. Today's lucky contestant is a green Stichodactyla tapetum aka "maxi" mini carpet anemone. I wouldn't recommend cutting a "mini" that's smaller than a nickel or a "maxi" smaller than a silver dollar. I don't have a good reason for these "rules," it's more of a "doesn't feel right" sort of thing. Do NOT attempt to cut these while attached to a rock. You will NOT get a clean cut. The halves need to be physically separated for proper healing. Place the anemone on to your cutting surface. Allow it to relax for a minute, round out, and release some of its water.
3. Carefully plan your cut. Ideally you want to create two halves of equal size. Find a line of symmetry. I planned making the initial cut along the blue line, and the secondary cut along the red.
4. Place the tip of your blade into the mouth (45 degre cutting angle). Pierce the tip all the way through until you feel the cutting surface with the tip of the blade. The anemone may tense up at this point, even spit out a stream of water. Holding the anemone in place by pinching it (see above), slice through the anemone from the mouth-out in one clean stroke. Throughout the slice you want to feel the tip of your blade touching the cutting surface to ensure a clean cut. (cleaner cut; quicker heal!)
5. Rotate the anemone around. Reposition your blade into the mouth again. Pinch and slice.
6. Allow the halves to "round out" in the water bath. S. tapetum does not produce a lot of slime... compared to other, larger anemones. Five minutes in the bath should be more than sufficient. If you've made a good cut, your halves will for "C" shapes quickly. You can now place the halves into your propagation tank. Discard the bath water! Keep the halves separated! To avoid infection, give the healing anemones good circulation and away from tankmates that may irritate them (fish, shrimp, crabs, etc.)
Final notes: The more "foot" you give a half, the quicker it will heal. 50/50 works best. Here's an angled shot of another S. tapetum post-cut.
Following the cut, the halves should close up around the damaged end quickly. This photo shows the undersides of the two halves of the anemone shown above.
I know a bunch of you are hunting for these cool little 'nems. I hope this helps!