The way it was explained to me, is you set a piece of rock over the middle of it so it can't go anywhere. However, you may have to shape the rock so that the oral disc is exposed. Anyway, in an effort by the anemone to get away it will split on either side of the rock. I have seen this done with leathers, toadstools, mushrooms and other types like them. Having seen it done with those corals it made sense to me when I heard it with anemones. From what I understand it is better for the coral because there is less chance for infection, because the coral splits by choice rather than being cut.