“The western pygmy marmoset (Cebuella pygmaea) is a marmoset species, a very small New World monkey found in the northwestern Amazon Rainforest in Brazil, Colombia, Ecuador, and Peru.” – Wikipedia.
The lifespan is said to be about 12 years and they can make good pets with patience! They are still primates and not dogs or cats. Personally, I don’t believe that they should be ‘pets’. They are our equals in many ways. I’d feel uncomfortable treating a pigmy marmoset as a ‘pet’. It probably would not work out anyway. They are better left in the wild to enjoy their freedoms.