Squat rhinos lived in North America about 12 million years ago, congregating in huge, water-bound herds much like modern hippos.

Dubbed the “bone collector,” this caterpillar found on a Hawaiian island disguises itself while stalking spider webs for trapped insects to eat.

A weathered sign in the Minnesota River Valley proudly proclaims: “World’s Oldest Rock.” Erected in 1975, it marks a 3.8-billion-year-old gneiss — or so scientists thought.