Also not common knowledge is that technically you could take it, put it in your blender, and any non-damaged cells will start to regrow the sponge
Not that I recommend this!
But you can do it on a larger scale. Basically if you just take a scalpel and make a clean cut underwater, you should be able to just cut off a branch. Then you can wedge it between rocks or use a light bit of fishing line to gently tie it across a rock. I suppose you could also try to lay a piece of rock next to a branch to see if it will adhere, and then cut below that branch to free it.
Overall I would say they are pretty adaptable to fragging in many ways.