I did find this similar thread:
https://www.backyardchickens.com/threads/a-worm-in-my-egg-photos.928587/
The conclusion there was that it was a very strange chalazae.
https://www.backyardchickens.com/threads/a-worm-in-my-egg-photos.928587/
The conclusion there was that it was a very strange chalazae.