Google is marking Earth Day 2013 on Monday, April 22, with what might be its busiest yet more subtle animated doodles.

Highlighting the Earth's complexity on the 43rd Earth Day, the doodle offers a snapshot of the four seasons our fragile planet experiences, as well as some of its flora and fauna, CNET says.

"Today we are celebrating Earth Day with an interactive doodle that captures a slice of nature's subtle wonders," Doodler Leon Hong wrote. "We hope you enjoy discovering animals, controlling the weather, and observing the seasons. Use the sightseeing checklist below to make sure you do not miss anything!"

Typically quite easy to identify, Google's name in the doodle is hidden among the landscape. What appears to be a lazy circle of flowers makes up the G, two caves make up the O's, while a stream leads into the second G and closing E. A lonely tree that represents the L grows taller with the changing seasons while the meandering stream drips off the edge of the doodle as if from a flat Earth.

Clicking on the Sun/start button over the mountains sets the landscape and seasons in motion. The sun will set, replaced by the light of the rotating moon. In fact, the doodle presents us with all phases of the moon: full, half, crescent, and gibbous.

And with each dawn, visitors are presented with another season, beginning in spring and cycling into summer, fall, and winter before its eventual return to spring, where, like on terra firma, the cycle repeats itself.

Like previous doodles, the Earth Day doodle is interactive. Clicking on the clouds will produce snow in the winter and rain in the other seasons. Mousing over the logo will produce a gentle breeze that obliterates the G before nature allows it to regenerate.

The doodle also has its share of resident wildlife that users can interact with: birds inhabit the sky, fish swim in the lake, a bear resides in a cave, ants scurry near the G flowers, and fireflies appear at night after a gentle rain, CNET says.