A Class L planet is a marginal planet. They have an age that ranges from 4-10 billion years and a diameter between 10,000 and 15,000 km. They are located within the Ecosphere of a solar system. A marginal planet is categorized by a rocky terrain and high amounts of greenhouse gasses. Class L planets usually once were Class K or Class M, and were altered by the introduction of destructive gasses. Class L planets can only sustain plant life, and are suitable for colonization by humanoids through terraforming.