There is a classic speculation in metaphysical circles that takes the concept "as above, so below" into the cosmos. According to this theory, the space between the stars is related to the space between atoms in matter. This view relates our sun and planets to the nucleus and subatomic particles in an atom, and by extension, life on earth to possible life on, say, a proton. Taken in the other direction, our solar system might be an atom in matter in a larger universe. So...we might have little earths built into the atoms in our thumb nail, while we ourselves might inhabit an atom in the thumbnail of some larger being.
I am no scientist and do not know enough to believe or not believe in this. But it is certainly amusing to think about.
Related, but not entirely on subject: There are no walls, floor, ceiling or any other boundaries to the universe. There is no end. Trying to wrap my mind around that concept is consistently entertaining.
"Hang in there. The light only comes at the END of the tunnel." [i]Letters to Oso, 2010