WordNet sense 1 (usually unbranched usually spineless cactus covered with warty tubercles and having magenta flowers and white or green fruit; resembles the related mescal; northeastern Mexico and southwestern United States):

Ariocarpus fissuratus

WordNet sense 2 (highly succulent stemless clump-forming plants with grey-green leaves similar in texture to lumps of granite; South Africa):

living granite, stone mimicry plant