This my alternate attempt and making a mouth. (Again...non functioning) This fish has a dorsal fin near the tail. I used a short section of cylinder to cut scallops out of the fin. I did about a dozen subtraction cuts. On the last one, the Boolean stopped working and the cylinder and fish body would disappear. I tried saving and closing out, then reopening. So far, no go. Then I tried intersecting a cubic shape with the fish body. Then I selected both and duplicated. My plan is to cut the lower jaw away in the upper model, then to do an 'intersection' with the bottom one which would leave only the lower jaw. But the model still disappears no matter which of the three Booleans I choose. How do I get past this?