What are the fireflies for and how to get them?

Per the Lion Studios reddit - "they are not yet required for anything so we recommend selling them for a bit of gold"

You have to win a Chest of Drawers by completing tasks, leveling up or getting rewards. The drawer knobs and drawers built from them combine to make a Chest of Drawers that can produce light bulbs, which combine to make lamps which produce Fireflies automatically and periodically.

I have yet to figure out what they are for. They take up space like trash cans but have much less selling value.