Fibonacci

When Fibonacci enters the battlefield, create one 1/1 Bunny creature token, and put one Birth counter on Fibonacci.
All other Bunnies get +1/+1.
At the beginning of your upkeep, create X 1/1 Bunny creature tokens, where X is the number of Birth counters on Fibonacci. Then, remove all Birth counters on Fibonacci, and put a number of Birth counters on Fibonacci equal to the number of Bunnies that were on the battlefield before your upkeep.