An assortment of postage stamps with images of Mahatma Gandhi (© PictureLake/E+/Getty Images)

The Roman amphitheater of Itálica near Santiponce, Spain (© Amazing Aerial Agency/Offset by Shutterstock)

Roman amphitheatre of Itálica, Spain (© Amazing Aerial Agency/Offset by Shutterstock)

Andromeda galaxy (© NASA/JPL-Caltech)

Boreal forest, Quebec, Canada (© Onfokus/Getty Images)

Huay Mae Khamin waterfall in Khuean Srinagarindra National Park, Thailand (© Casper1774Studio/Getty Images)

Common octopus in sea grass off the coast of France in the Gulf of Lion in the Mediterranean Sea (© BIOSPHOTO/Alamy)

Common octopus off the coast of France in the Mediterranean Sea (© BIOSPHOTO/Alamy)

Rainbow abalone shell, New Zealand (© Lynda Harper/Minden Pictures)

Red pandas in cloud forest habitat of Singalila in West Bengal, India (© Ben Cranke/Minden Pictures)

Saint-Malo in Brittany, France (© Mathieu Rivrin/Moment/Getty Images)

An ichthyosaur fossil of the Jurassic period, Dinosaurland Fossil Museum, Lyme Regis, Dorset, England (© Christopher Jones/Alamy)

Saguaro 'family' and Milky Way, Saguaro National Park, Arizona (© Christian Foto Az/Shutterstock)

An artisan applies final touches to an effigy of Ravana in Jammu, India (© Mukesh Gupta/Reuters)

Aerial view of the Temple of Hatshepsut near Luxor, Egypt (© Ratnakorn Piyasirisorost/Moment/Getty Images)

The Wapizagonke Lake in La Mauricie National Park, Quebec (© Instants/Getty Images)

Capel Curig in Snowdonia National Park, Wales, United Kingdom (© Sebastian Wasek/Sime/eStock Photo)

The Fanal Forest on Madeira Island, Portugal (© Val Thoermer/Alamy)

Brown-throated three-toed sloth in Manuel Antonio National Park, Costa Rica (© Lukas Kovarik/Shutterstock)

Bald cypress and Spanish moss in the Atchafalaya Basin, Louisiana (© Chris Moore/Exploring Light Photography/Tandem Stills + Motion)

Bald cypress and Spanish moss in the Atchafalaya Basin, Louisiana (© Chris Moore/Exploring Light Photography/Tandem Stills + Motion)

Eurasian scops owl in Bohemian Switzerland National Park, Czech Republic (© Milan Zygmunt/Alamy)

Bavljenac Island, Croatia (© Julien Duval/Amazing Aerial Agency)

Virupaksha Temple framed by two huge rocks in Hampi, Karnataka (© Travel Wild/iStock/Getty Images Plus)

Red fox in the Black Forest of Germany (© Klaus Echle/Minden Pictures)

A pumpkin patch in Newton, Massachusetts (© Frank Debonis/EyeEm/Alamy)

An unkindness of ravens in Juneau, Alaska (© Brian Browitt Photo/Adobe Stock)

Misty pine forest in the Central Highlands of Vietnam (© Thanh Thuy/Moment/Getty Images)

Grotesques at York Minster, North Yorkshire, England (© John Potter/Alamy)

Dyavolski Most (Devil's Bridge) over the Arda River in Bulgaria (© Petar Mladenov/Alamy)