Select an animal, insect or other creature that you find particularly interesting or inspiring. Make notes of what you know about its life cycle. If you need, you can take a quick peek at an encyclopedia or online reference site entry; don't get bogged down in details. You just want to have a serviceable outline.
Use your outline to write a story, essay or other piece in which the creature's lifecycle acts as a metaphor or features in some other way, great or small, in the piece.