I am a succulent that resembles a rock, native to arid regions of South Africa. What am I?

1. My leaves are often paired and have a pebble-like appearance.
2. I thrive in extremely well-draining soil and prefer bright sunlight.
3. I produce daisy-like flowers that emerge from the center of the paired leaves.
4. I am often used by gardeners and collectors because of my unique shape and texture.