In 1787, Atanasio Echeverría y Godoy was part of the Royal Botanical Expedition to New Spain, an exploration of areas throughout what is now California, Mexico, Cuba and Puerto Rico. He created hundreds of drawings of the plants they discovered and cataloged, including this group of succulents.
There are about 150 species of Echeveria, most of which feature the beautiful rosette design. They are sturdy plants that can be grown in the shade, but can also take some frost. All the species are drought-resistant, but they tend to grow better with regular watering and fertilizing.
Most species lose their lower leaves in winter. Since these droppings can be fertile ground for a fungus that can then attack the plant, you should remove them regularly.