Pretty forbidding looking, isn’t it?! I would guess the ground squirrels give it a wide berth — or can they burrow under it and be well-protected?
Some kind of cactus. Or, as E.B. White might have penned, “Some Cactus!” Our unseasonably warm weather must be making it thirsty. A drizzle might descend in the next day or two, and that just might turn this from dusty gray-brown to a more vibrant green. I’ll check it out. Eventually.