Known as "living stones", because their highly succulent, usually stemless, blue-green leaves occur at ground level and can resemble small stones. They form small clumps of a few or many paired, usually cylindrical to egg-shaped leaves that are cleft in the center. Each stem bears just 2 leaves per season but may produce offsets over the years. In some species, the old leaves persist and form a short column on which new leaves develop. Solitary daisy-like flowers, usually white, yellow, or purple, appear in the cleft.