A curious cuttlefish stares back at the camera from inside The Smithsonian's National Zoo Invertebrate Exhibit. The exhibit, home to dozens of small aquatic and terrestrial species without backbones, closed on Sunday. Meghan Murphy/Smithsonian's National Zoo hide caption

itoggle caption Meghan Murphy/Smithsonian's National Zoo

The fossilized remains of a whale that washed up on a shore in what's now Chile more than 5 million years ago. Vince Rossi/Smithsonian Institution hide caption

itoggle caption Vince Rossi/Smithsonian Institution