Snowballs from Hell

How appropriate the desert's midsummer snowballs happen to be covered in spiny coats.  Two of my barrel cacti have sprouted herds of baseball-sized buds, and I need to do some research into what's going on.  I'm not sure if it's a bad thing, a good thing, or just one of those things, nor whether it was preventable, or even something I'd want to prevent.  But they do make interesting looking "snowballs!"