when "black destroyer" was incorporated into "the voyage of the space beagle", several changes were made in coeurl's anatomy and physiology—for example, coeurl's tentacles originally ended in tentacled fingers, but were changed in the novel to suction cups, and the dietary chemical was changed from phosphorus to potassium. in the novel, it is theorized that the members of coeurl's race were pets or servants of the original inhabitants of the planet.