The mayfly does not serve as a metaphor for the fleeting, rather, we would like to approach it as an embodied entry point, a “companion species”, into the ecological, material and infrastructural conditions through which ephemeral forms emerge. The Ephemera danica unsettles anthropocentric assumptions about temporality, fragility and endurance. For instance, what appears as a “brief” lifespan is only brief from a human-centered temporal frame; seen within its ecological lineage, the mayfly’s life cycle exemplifies generative instability – a mode of existence in which mortality sustains continuity and transformation across multigenerational, more-than-human timescales. Its emergence patterns, dependencies, and rhythmic recurrences draw attention to the interlocking processes that constitute “ephemeral” phenomena, revealing temporal duration as intrinsically relational, distributed and ecologically co-produced.