Square right here

One morning the Zinger Pinger went outside and found something very strange in his garden. It looked like a balloon but it was square. “I’ve never seen something like this before,” said the Zinger Pinger. “How did it get here? Hmmm… I wonder what I could use it for!” Where did the square balloon come from? Did it grow from a seed buried in the Zinger Pinger’s garden for many years? Or is it some sort of message balloon blown to Zingulu Island by a rare rectangular wind?