As marsupials, kangaroos have pouches called marsupiums that provide nourishment and protection for their undeveloped young. When a kangaroo mother gives birth, her blind, jellybean-sized newborn must climb up into the safety of her pouch to nurse. There it will feed and grow for nine months before it’s mature enough to begin exploring the world beyond.
A baby marsupial of any kind—kangaroo, wallaby, koala, Tasmanian devil, wombat, possum, etc—is known as a joey. Next, watch a baby koala joey peek out from its pouch, see how a baby echidna (a puggle) hatches from an egg, and from TED-Ed: The three different ways mammals give birth.