19. Star Trek Tribble

Tribbles are native to the planet Iota Geminorum IV. They are essentially small bundles of fur with no visible external features. Their fur colors range from solid white to grey, speckled light to dark brown, yellow to reddish orange, and black. Their only two purposes in life appear to be to eat and to reproduce, and they perform both of these functions extremely well, as Lieutenant Worf states "If you feed that thing the smallest morsel of food, in a matter of hours you'll have.....ten tribbles, then a hundred, then a thousand." Though they are "born pregnant" they will only reproduce when conditions are favorable. They will even reabsorb their young in harsh conditions. Dr. McCoy took time to examine some tribbles, concluding that they use over fifty percent of their metabolism for reproduction. Instead of generating waste, a Tribble gives birth to another Tribble. The population on their home world is only kept in check by the abundance of predatory reptiles

Mother tribble measures 6" in diameter and purrs when squeezed