Radiolaria are microscopic protozoa, typically about a tenth to two-tenths of a millimetre across, that build intricate mineral skeletons. They drift as zooplankton throughout the world's oceans, and their skeletal remains form much of the siliceous ooze that covers the ocean floor. In 1862 the German biologist and artist Ernst Haeckel published an illustrated monograph on these organisms, drawing their varied forms with exquisite line work. The book was an early major achievement of his scientific career and a visual catalogue of forms too small to see with the naked eye. Haeckel's artistic skill made the hidden geometry of plankton visible to a wide public, though his later theories on race and eugenics are now widely condemned.

Hampi is a UNESCO World Heritage Site in Karnataka, India, with more than 1,600 surviving remains spread over 4,100 hectares. It was the capital of the Vijayanagara Empire from 1336 to 1565. Travellers from Persia and Portugal described it as a prosperous, wealthy and grand city with temples, markets and farms along the Tungabhadra River. By 1500 it was estimated to be the world's second-largest city after Beijing, and probably India's richest at the time. In 1565 a coalition of Muslim sultanates defeated the Vijayanagara Empire, its capital was conquered and destroyed, and the city was left in ruins. Hampi remains a religious centre, with the active Virupaksha Temple at its heart.