A bubble can can look like a world.
Bubble: 1) a thin, liquid sphere, filled with air or another gas; or 2) time limited good fortune that is isolated from reality.
Writing prompt: create a 150 word story titled The Bubble, in which the character(s) have been living a seemingly idyllic life, isolated from reality – until a triggering event changes everything.
Foreshadow the ‘trigger’ in the opening sentence.