I know i buck the trend when it comes to this idea. But i strongly believe that a lot of our "missing matter" that is the basis for "dark matter and dark energy" is exactly objects like this.
Too small for us to detect with our instruments, yet all over the place.
This explains: 1. why our mass calculations for galaxies appear to be WAY low.
2. why "dark energy" is inconsistent across space.
There is simply shitloads of mass out there that is either never enough material to form a star, or made up of materials that will not fuse into a star (Iron and heavier).
I think dark matter and dark energy are the "Aether" of the 21st century.
		
		
	 
Dark matter is better understood than that.
Dark energy is mostly a name to explain that which we cannot describe any other way, and generally accept to represent one or more discoveries we'll understand in time.
Dark energy, imho, is likely to be something like: "oh, we can get this and that to do such and such... but we just don't understand at all how and why that outcome happens" and the knowledge will eventually be discovered, linking the unknown variable to a concrete element of reality. From there, that missing "link" will be applied to other mysteries and the mysterious will become better understood.
Dark matter I think is a little more concrete, in that certain things line up knowing that there is this element that we can account for, but cannot otherwise see or truly understand just yet. 
One of the last things I remember reading about it, is that there is a certain distribution of it throughout the cosmos, in a certain pattern, and the "spread" of the matter we know slightly lagged behind it and then followed it to start "clumping" in certain ways at certain regions of space.
I'm fairly certain all matter, including rogue planets, stars, and interstellar "dust" is essentially accounted for. As in, even the matter that is best described as molecules/particles just floating randomly between larger gravity-bound bodies.