This cactus has died in the middle. If you can tell from the photo, it has died in two places, with a little bulb in the middle still alive. The top section of live growth has now put out a little white root. So I have some questions. At some point should I cut off the top section that has the root and plant it? If so, wait a while for more roots to grow? What to do with the small middle section? Cut it off, wait to see what happens? The bottom section - is it trying to die off, or might it continue to grow? What would have caused this to happen? Is it a normal thing t happen? Did I not water enough? Thanks.