So the piece that broke off is a hoya? Most succulents, if left in a cool and dry place (like a cookie sheet out of the way), will scab over and sometimes even sprout roots. There are some succulents that will root in water like most plants, but they are few and far between. I always cut off the overgrown parts and let them scab over, once they are all scabbed and protected, I would plant them in moist soil (always make sure that you mix your soil with water BEFORE planting, otherwise it won’t ever hold water like it’s supposed to). If you take cuttings and put them right in soil, they usually rot and die. 😦 So, since I’m a botanist…did that help? 🙂