This is s a mimicry plant know as "African living rock" or “Splits rock” because it imitates split chunks of granite (especially if grown in full blazing sun) It resemble stones so closely that it can only be found with difficulty.

Family: Mesebrianthemaceae (Aizoaceae)

Scientific name:  Pleiospilos simulans (Marl.) N.E. Brown 1926

Origin:  South Africa (Cape Province: Aberdeen)

Habitat: Grows in rock crevices in areas with about 300 mm rainfall per annum in March and November where light is usually bright and unpolluted.

Vernacular Names: Split Rock Plant, Liver plant, Stone plant.

Etymology: The genus name is derived from the greek words pleios (full) and spilos (dots), which refers to the many dots on the plants.
The species name “simulans” come from a Latin word meaning "imitating"  or "resembling" for having the resemblance of pieces of rock.

Taxonomic Synonyms:

• Mesebrianthemum simulans Marloth 1907
• Pleiospilos leipoldtii

Pleiospilos simulans is a mimicry plant know as "African living rock" or “Splits rock” because it imitates split chunks of granite (especially if grown in full blazing sun and in time of drought) It resemble stones so
closely that it can only be found with difficulty.
 

Description: Pleiospilos simulans is a slowly clump-forming succulent and one of the more unusual Pleiospilos species. One of the largest of the species suited for hot sunny positions.
Stem: Stemless or very short with 1 to 3 branches (Often more brached in cultivation)
Body (Leaves) : The body of the plant consists of 1 or 2 (but sometime more in cultivation) pairs of leaves. The leaves are grey-green to brownish-grey, triangular in cross section, very flat-opening, spreading, heavily keeled reminiscent of a wide-open serpent's jaws, broader than thick, about 7- 8 cm long, 3 cm large and 2 cm thick. The leaves are not as symmetrical and firm as the others Pleiospilos and fleshy with the consistency of rotten meat or weird rubber. The epidermis has a texture like sharkskin looking something like a cross between a Gasteria and a Lithops, with numerous dark-green dots on the upper surface.
Flowers: Scented, daisy-like, yellow to orange flower with a white centre, Considering the size of the plan they are extremely large (up to 6 cm in diameter), sometimes in group up to 4 borne on short pedicels
Blooming season: Late summer or early autumn after the summer dormancy period. The blooms open in mid-afternoon and close just after sunset.
Fruit: Mostly 12 loculed.

Cultivation: Pleiospilos nelii is a very adaptable plant, it will grow whenever it has water and good sunlight, but it will become dormant in very hot weather to conserve water. It need full sun to light shade with a very open compost that drains quickly. The container should be at least 10 cm deep to accommodate the long tap root. Very little water is needed during the growing season, and we do not fertilize the plants. In late summer to early fall before nighttime temperatures fall, watering of the plants is stepped up to once a week. When the nighttime temperatures drop to 9°C, watering is restricted throughout the winter months. In the winter, it grows new leaves from the center of the split, and the new leaves then consume the old leaves. If the plant is over watered, the old leaves remain and the plant usually rots and dies. Not to water it when it is splitting, just leave it alone. Even with no watering the leaves don't shrink and prune up like some succulents do when they are not watered they stays plump even after several months with no water. For an idea of how succulent these plants are, a mature specimen can easily go a whole year without any water in a typical European or North American climate. If the plants are grown correctly, ideally there should only ever be 2 pairs of leaves. The lower ones are the previous years, and the top ones, the current years. One sign of good care is a firm, round, symmetrical plant with no old leaves still attached at the end of summer. The plants are hardy down to -5°C.

Propagation: Seeds or by division in early spring before new growth starts. One should not divide clumps too often because they bloom best when crowded.

Sometimes Pleiospilos will even be labelled as a Lithops, but it isn't the same. There are three immediate visual differences: P. nelii does not grow buried to its neck in the ground; it is bigger than any Lithops and will produce multiple flowers at once, something that Lithops never do.