This poem by Henry Johnstone is also a riddle...
Unless you blow, I cannot live,
And if too rough a puff you give,
I perish then and there:
But gently blow, and I shall grow
Till I am big enough to go
A-sailing in the air.
I'm round and light, and though my skin
Is very soft and very thin,
Its colors may compare
With those that, when the conquering sun
Bursts forth before the rain is done,
Adorn the rainbow fair.
Answer: A bubble!