big pig peaches

Dark matter is probably not made of anything you would notice if it were piled in front of you, except it couldn't be in a pile in front of you because it would fall through the surface of the earth.

There were theories of dark matter that had it composed of normal matter than you can touch. The term is "baryonic dark matter." Various tests have ruled out broad classes of baryonic dark matter. For example, if dark matter were made of stray planets we would notice a much higher rate of gravitational microlensing.

We can only speculate if the speculative dark matter in the article can even form piles. Physical constants have to be precisely tuned to allow a universe like ours, with stars and rocks and jellyfish. If dark matter is like ours but the strong and weak nuclear forces are a bit weaker, dark stars don't form. Dark black holes, maybe, but not dark stars. I assume the "no hair" law says dark black holes look like light black holes and decay into an equal mix of light and dark particles, which suggests an interesting way to test theories of dark matter. Create a black hole, count the decay products, measure the mass, and see if some mass goes missing. This is similar to how neutrinos were discovered.

We can also put some limits on what dark matter is by comparing theories of primordial nucleosynthesis to observed element abundances. Non-baryonic dark matter has to be something really weird.

Why should the number of types of matter stop at two? Maybe the ether quantum field has an infinite number of dimensions / degrees of freedom. We're using a bucket of them for our own universe (light). A parallel universe (dark) uses another bucket, but shares gravity with us. And then there's the mauve universe which doesn't interact with our own but does interact with the dark and cyan universes through the squiggly and squishy forces. And if we look close enough there may be two types of dark matter detectable by us.

I sense full employment for future particle physicists. We need a bigger particle accelerator to properly probe these alternate universes. (But see Einstein's Bridge as a cautionary tale.)