Might want to pry the crack in the rock open, I have had to break rocks with a screw driver (clean never used anywhere else) to move corals. Another way is go to yourlocal dentist offic and ask them if the dispose of there surgical tools if so ask them to save you a set. There is a tool that looks like a rounded chisel but has a really sharp edge. Take that rounded edge and push it under the ricodea at an angle so you don't cut it, basically pushing into the rock and it should cut right into the rock and free the ricodia.