Make a sketch of an object. Perhaps something in your immediate environment that you might think of as a curio or could imagine as an heirloom. Now transfer that object to fiction. Let it be the only intimation of the contents of a new fictional story.
Write a short description, in a few sentences at most, of the object’s immediate provenance—where it came from, how it came to be in the room.
Then write a short description of the object’s origin—where it was fabricated.
Then write a short description of the object’s prehistory, possibly the prehistory of all objects of this particular type—how it came to exist or be invented.
Then repeat the process but toward the future, writing first where the object moves next (and by whose hand) when it leaves the room, then where the object is when it is finally destroyed or decayed, and last, how objects of this type are thought of far into the future.
Look over what you’ve written and make notes toward a point in time where this object might appear in a story, whether that’s making its way into something you’re written, or in a story that hasn’t yet been generated. If you want something more, set a timer for fifteen minutes and write a sketch of that story in a compressed overview, or write the first pages of that object’s appearance in the story. Pay attention to the ways the object interacts with the deeper-time flows of creation and destruction in the world of your story.