I'm looking for help on how to parent/join this helmet:

[![enter image description here][1]][1]

With this skeleton rig:

[![enter image description here][2]][2]

Sorry if it's super simple I just can't seem to figure it out for the life of me. I feel like it's obvious but whatever I try it doesn't parent with the rig when I try to animate.

[<img src="https://blend-exchange.giantcowfilms.com/embedImage.png?bid=2076" />](https://blend-exchange.giantcowfilms.com/b/2076/)

  [1]: https://i.sstatic.net/pj9Pm.png
  [2]: https://i.sstatic.net/YARQI.png