I want a soft coral to grow on my back glass, and I am considering daisy polyps. Are they controllable like GSP? I want a good grower, but nothing invasive like blue clove or Xenia. These guys are pretty and I've seen mixed reviews of them; some saying they can be invasive, others, the opposite. I'd like to try them but only if I can keep them contained on my glass away from the main rockwork.