Celestrial Worm Ufo
Here's two right next to each other.
This one seems to stay in somewhat the same shape and is almost spinning like a fan.
I thought this one was interesting, here are some clouds creating a worm shaped cloud out of some sort of solar vortex. That would explain the changing of shape, size and color. It even moves like a worm. But if they are formed by clouds then how can you explain the worms spotted in a crystal clear blue sky? Besides this next video shows one that looks black with a light illuminating on one side.
These things are strange to say the least. Someday it will all make sense.
Reference: mystery-sky-lights.blogspot.com