Rosie's Special Surprise

Nosy Rosie liked to know everything about everything, but Daddy Rabbit was planning a special surprise. Nosy Rosie kept trying to guess what it could be, but Daddy Rabbit only smiled and said, "Wait and see." But Rosie couldn't wait, and hopped off to look for it. The scampery, skippity squirrel said it was shaped a bit like an acorn. The burrowy-tunnelly moles said you could go inside it. The flittering-fluttering birds said it was blue...What could the surprise be?