Google, known for celebrating significant days with its doodles, celebrates Earth Day showing five different biomes from around the world. The doodles are done in a way that one has to concentrate to figure out how Google is written.

In Friday’s doodle created by Sophie Diao, the Google logo morphs to depict a polar bear in the tundra, a red fox in the forest, an elephant in the grasslands, a tortoise in the desert and an octopus in the ocean – with a different one appearing each time one visits the site’s homepage.

“The vastness of the Earth’s diversity makes it an intimidating topic, but in the end I chose to highlight the Earth’s five major biomes,” doodler Diao said in a blog post. “On a day like this, we remember and celebrate our home in this great and stunning ecosystem.”

Earth Day, observed annually on April 22 since the event began in the late 1960s, is “the one day that transcends culture, language, and tradition,” Google said, explaining the significance of its series of Google doodles celebrating our planet.