rock beauty
/ˈrɒk ˌbjuːti/noun
1An alpine plant, Petrocallis pyrenaica (sometimes called Draba pyrenaica), of the family Brassicaceae (Cruciferae), typically having pale pink or lilac flowers. Now rare.
2A yellow and blackish-brown angelfish, Holacanthus tricolor (family Pomacanthidae), found on coral reefs in the Caribbean.
Origin
Late 19th century; earliest use found in William Robinson (1838–1935), horticulturist and publisher. From rock + beauty.