Conophytum calculus aka Conophytum Calculus

Conophytum calculus is a small succulent, part of the Aizoaceae family. People call it marble buttons and living pebbles. It comes from the Western Cape in South Africa. There, it grows in southern Namaqualand. Its range runs from the Knersvlakte north to Bitterfontein. It grows among quartz stones on dry land. Soft winter rains break the long summer drought. Mining has harmed parts of this habitat. Work to extract gypsum has caused harm there too.

The plant forms tight, low mats as it ages. These can reach about 0.49 feet [0.15 metres] across. Two joined leaves form each round body. Bodies stand about 0.05–0.07 feet [0.016–0.020 metres] high. They can reach about 0.08 feet [0.024 metres] wide. Some look like small balls. Others have sides that are a little flat. A tiny cleft, or split, marks each body's top. Its stone-like shape helps it blend into the quartz beds.

The leaves range from chalky grey-green to pale blue-green. Some have a purple-blue shade, and some show ribs. Most lack dark dots or stripes, though scattered spots occur. Small and large forms differ in body size. Each body looks like a pebble, with its smooth, round skin. White quartz bounces sunlight back around these small plants. This keeps the ground cooler than nearby dark sand and rock. The pale bodies blend with the sand's colour too.

Yellow flowers come through the small opening in autumn. Some have yellow-orange petals with brown tips. Each flower measures about 0.04 feet [0.012 metres] across. The blooms open at night and give off strong scent. The scent draws moths, which carry pollen between flowers. The blooms stand out against the pale leaf bodies. These bodies have almost no marks. The round leaves and night blooms help set this species apart.

Growth centres on late winter and lasts into late spring. The plant rests in summer as new leaves replace old ones. This cycle fits its home's dry summers and winter rain. LLIFLE says the species is easy to grow. It also names pots as the best place to grow it. Its small size and tight mats suit pots. The supplied evidence for this species gives no firm hardiness limits. It gives no known food use backed by evidence. Nor does it assess whether the plant is toxic.