Thanks for your comment.

Actually, dark matter weakly interact with normal matter. In most of the time, nothing happens. However, in very rare events, dark matter interacts with normal matter and these are our hope to directly detect it. There are various experiments on Earth trying to detect these very rare events. For the moment, nothing has been found, but hopefully, something will be found at some point in the following years :)

In the same way, dark matter can self-interact and produce visible stuff. This is how cosmic rays are used to indirectly search for dark matter and this is (one of) the mechanism responsible for the relic density of dark matter present in the universe.

Of course, all of this assumes that there is dark matter.

I hope things are now clearer. Otherwise, do not hesitate to come back to me ;)