Use a gravel-rich cactus potting mix for this plant, ensuring good aeration and drainage. Water sparingly, from its base and into the soil. Keep this cactus warm, away from drafty windows and air vents. Fertilize every few months during growing season. Keep in full sun or a bright window.

Whether you live near the ocean or far from it, you can have a living "sand dollar" or "sea urchin" to admire. This squat cactus is dark green with divisions that radiate out from the center, pizza-pie style. Tiny white dots decorate each section, and fuzzy raised dots add more visual interest and help it to look like even more like one of the sea creatures for which it is named. This is a cactus that flowers and fruits. It causes no trouble, due to its lack of spines. And it takes care of itself, for the most part. It is a magical cactus for a child, or to delight the child in each of us.