If you have locking needle-nose pliers, you might be able to get a good bite. Lock it tight and slowly rotate counterclockwise.

If that doesn't work you could try the dremel tool method to cut a flathead screwdriver slit.

When I read their initial setup, I wondered how tf they could rack focus from the plants to the mountains during a single shutter click without lens warping or any blurring.

Yes that is, by definition, multiple exposures but at different focal planes.