The pygmy marmoset the smallest true monkey in the world. 

It typically grows to 6 inches in length and weighs about 4 ounces. This quadrupedal monkey lives in the rain forests of Brazil, Colombia, Ecuador, Peru, and Bolivia.

In the wild, these little guys’ lifespan is 11-12 years. In zoos, they can reach the ripe old age of 20 years.

Nicknames for the pygmy marmoset include pocket monkey and little lion.