Mayfly
An insect that lives a single day in its adult form — a whole life compressed into one bright span.
A mayfly in a dream is the dream's image of a whole life compressed into one bright span. The mayfly emerges, mates, and dies inside a day; there is no time for a second attempt. The dream brings the mayfly when something in your life — a brief connection, a short stretch of brilliance, a piece of beauty with no follow-up — is going to be entirely contained within a window that will not be repeated. A mayfly seen mid-air in the evening light is the dream affirming the brief, complete life. A mayfly already dead on the still water, the day done, is the dream noting that the short window has closed and what was going to happen in it has happened, fully, exactly once.