Could Hallucigenia be the echinoderm missing link?

Mostly: We, here, are not competent to explore this idea properly. If you’re serious, bring it before the community of experts and/or hit the research journals to see if it’s already been considered and what the outcome thereof was. (I’d bet dollars to donuts that it has been looked at and that there’s a good, well documented, summary of the analysis available if you ask practitioners rather than laymen.)

If it turns out that there isn’t a previous discussion, great – those are still the people you’re going to have to get involved in analyzing whether your insight holds water or is simply all wet.

You’ve got a thesis. Now you need testable hypotheses which will support or refute it, and you need to perform those tests. Until you take it to that stage, it’s all handwaving and hope and guesswork.