One of my favorite fiction stories with a butterfly was a time travel short story from the 60s or 70s or whatever. Before my time but it was at the library.
They had to be very careful not to bring anything from the past into the future or it would wreck things.
But a little butterfly got caught in a tiny pocket of air between the ship and the time stream and made it into the future.
And the butterfly started a series of events that unraveled the further future. It was pretty amazing actually.
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