I've had this hedgehog (Echinocereus) cactus for about three years now. It initially was just the large cactus in the middle of the dish. I keep it in the house or garage during the winter months, then put it outside each summer.
Last year, I put the plant in the front of my house, which faces west. While I was watering my other plants, I noticed something on the cactus that looked like a small cotton ball or a piece of lint. I tried to remove it, but I couldn't. Later, I saw a stem growing on the cactus, and I realized that the 'cotton ball' was part of the cactus.
One day in mid-August, when I was walking out to the mailbox, I saw a beautiful bloom on the cactus. I can hardly wait to see what it does this year.
I researched the hedgehog cactus, and I found that it grows to 15 inches and blooms in spring and summer. It likes sun and partial shade, and it has free branching clusters on mounds of erect stems. The flowers can measure up to 4 inches across. I didn't actually measure the bloom on my cactus, but it certainly looks like it could be that wide. The blooms can appear from the base, or from the sides of the plant, like this one.
The hedgehog cactus is a popular plant because it's tidy and compact. But it's the dickens to move. I usually end up getting stuck a few times before I get it to its new location.