[hymenopter4]

Dark matter has yet to be defined as anything other than an observed effect on the behavior of matter. Something (and indeed a thing, if anything, ergo matter) we think is probably there.

Being a theoretical hypothesis, formed to explain observations, it remains a side-effect of accounting and inference, and has not been located directly.

Show me why you believe it is a thing. Show me where you have found it. Tell me why it isn't actually matter.