This Month in Photo of the Day: Nature and Environment

Bleached by high water temperatures, this bubble-tipped anemone is largely devoid of the algae that provide color as well as energy from photosynthesis. Though stressed, it will likely survive and continue to serve its clownfish.
—Premnas biaculeatus (spine-cheek clownfish); Entacmaea quadricolor; Papua New Guinea

See more photographs from the January 2010 National Geographic feature story "Beautiful Friendship."