Final answer:
The answer to the riddle is a Watermelon. When unripe, its exterior is green, but when ripened, it turns red. The fruit inside is red, but the seeds, which are spit out, are black.
Step-by-step explanation:
The answer to the riddle is a Watermelon. When a watermelon is unripe, its exterior is green, but when it ripens, it turns red. The fruit inside the watermelon is also red, but the seeds, which are spit out, are black. This riddle plays with the colors and characteristics of a watermelon to confuse the reader.