I would work at it pealing them away with a small 1/4" chisel or a sharp flat screwdriver. Right now I'm tearing them away with a tweezers from a rock I'm trying no make a mono polyp sp not caring if I loss the polyps I remove, and they still recover nicely. Propagators will usually use the chisel/screwdriver, or the nip just the heads off with scissors into a settling tray, but that method doesn't suit your needs.