Once in a while something good comes out of an accident in the garden. About 8 years ago I stepped backwards right onto a single lace cactus, Echinocereus reichenbachii, smashing it into the ground. Imagine how sick I was at the time. Never fear. Cactus are tough. It divided itself into 3.
Then this mamillaria. Workmen knocked the pot off the wall smashing the top off the cactus. I dried off the broken top and repotted it and left the broken one to heal. That broken one has healed over and has now made a whole new family.
An unwary boot trampled this agave into the ground. It, too, has produced a new family. I am not sure this one is a good thing.
I have often wondered what makes the barrel cactus suddenly start producing multiples on top of itself. Like this one I saw in Arizona. It is quite obvious that the top of the plant has been subjected to some damage in the past. It has made a new top and lots of babies around the sides.
Cactus can take a lot of abuse but sometimes an accident turns out to be a happy event.