Fire fruit was a fruit native to Kelemane's planet. In early civilization, before the arrival of the "Ground Shaker", these fruit were often offered as gifts to the god Tahal. When the new god arrived, earthquakes began, and the fire fruit was only offered to the the "Ground Shaker". Centuries later, the people stopped believing in the old gods, but still held the superstition that it was bad luck to eat the fire fruit. (VOY: "Blink of an Eye")
The fire fruit was depicted by a Tamarillo, a South American fruit sometimes found in Los Angeles groceries.