I saw a black wavy trapezoidal-shaped object rise up from tree line north of my house and then move west.

Sitting in my backyard, I heard a plane go over and looked up to see it. I saw the plane heading west in the north but below it was a black trapezoidal shape wavy object that seemed to be rising up to it. It looked like a giant black manta ray swimming upwards and I assumed it had to be a balloon or vinyl sign that had ripped free from a business and caught in the wind. But it started moving west and looked like it was changing shape. I stopped filming when it went below the tree line, thinking it was gone, but then I saw it a few seconds later in the distance farther west. I filmed it because I didn’t and don’t know what it was.