Yes, they can be cut into pie shaped pieces, but they will grow into an odd shape because the larger pie section will always be apparent. A riskier (but more profitable) way to frag them is to damage the coral sufficiently that instead of attempting to regrow, it produces numerous anthocauli, or daughter colonies, that grow on the plate until they are large enough to separate and grow on their own. A plate may continue to produce anthocauli over and over again.