brief, deciduous, ephemeral, evanescent, flash, fleeting, fugacious, fugitive, impermanent, passing, short-lived, temporary, transient, momentary

Her blue beach umbrella goes tumbling across the beach and
Into the ocean
I could have been right behind it but
I hesitated
I looked at my compression stocking
I heard my screaming children
I retreated
I regrouped
It collapsed
Glimmered for a moment
A spot of brighter blue and then
Disappeared into the waves