Bunnies to Jumbo Rabbit - Sponge

Mr. Rabbit from Magic A small sponge rabbit is placed into a spectator's hand.
When they later open their hand, now there are two rabbits! One of the rabbits is placed
into the magician's pocket and the spectator closes their hand around the other. Again,
when they open their hand, another rabbit appears! The two rabbits multiply again, becoming four!
As a finale, the four rabbits all change into one large "Mr. Rabbit."