A watermelon radish. It resembles a turnip and a mini watermelon. It grows 3-4" in diameter. I've never had one until today. Maybe because I am not a fan of the "fire" typically associated with radishes. However, the flesh of this heirloom radish is milder and sweeter. According to my Internet research, the watermelon radish loses its pungency as it matures, unlike many other radishes.
Thinly sliced or grated raw as a salad ingredient, the flavor is reminiscent of jicama. Alternatively, it can also be roasted like a turnip and mashed like a rutabaga, but it will lose its amazing color in the cooking process. If you grow them in your garden from seed, or you purchase them directly from a local farmer who hasn't trimmed the tops, eat the greens as they are a good source of calcium.