Chasmatophyllum musculinum is not shy of accepting rocky protection. Plant health is often enhanced in fast-draining, rocky soil, minimising the chances for root rot and fungal issues. The tendency of exposed rock to absorb heat during the day and releasing it slowly at night moderates temperature swings, beneficial for root protection and extending flowering seasons.
Competition from too many close-growing other plants is less among rocks. Reducing the direct sunlight hours upon the plant is a benefit for some, while trampling by animals is also reduced (Frandsen, 2017; Smith, et al, 1998; iNaturalist; https://www.worldfloraonline.org).