Alien.
The iconic, alien species from the Alien franchise, known as the Xenomorph has one of the most inaccurate lifecycles.
The xenomorph has 3 lifecycles
Egg -> Facehugger-> Chestburster-> Xenomorph.
The xenomorphs grow so fast, like really fast. They can grow into adults within few minutes or hours.
I find that highly unlikely to happen because a living organism can't reach adulthood so rapidly and without consuming anything.
The human hybrid xenomorph grow into adults in just few minutes. Growing upto 2.30 m tall just after being born.
A perfect organism still need time and energy to grow.