Lithops or Living Rocks, thrive in low humidity, need infrequent watering and care, and are relatively easy to grow succulent plant, Lithops are popular novelty houseplants. With their small size and slow, compact growth these plants do not take up much room. Lithops are long lived – up to 40 or 50 years. It is quite possible to keep a plant in the same pot for 10 or 20 years. Lithops are non-toxic to humans or pets.