This idea is a minifigure habitat with a day-dreaming cloud above it. In this example, the lowly pirate is daydreaming of golden riches. The cloud could be used for all sorts of other dream situations, though - remembering the past, nightmares, planning the next day, envisioning a future wedding, etc.
The cloud is built with studs-not-on-top (SNOT) techniques to look pretty rounded. The weight of the cloud is supported by the minifigure habitat wall, connected to the back left corner. Clear and white 1x1 round plates are used to create thought bubbles connecting the dream to the figure. There is a simple black slope and tile base surrounding the bottom scene.