Floating potato/oval

I was driving east on the m65 when I saw a floating oval/potato shaped object in the sky.
It moved really strangely to the right, quite a distance in very little time. I say very strangely because it was very smooth and almost instant. It then shimmered, like a wave, like it was reflecting light almost. It was then that i could see the full shape of it, which was a potato/ oval shape.
It then just disappeared. I genuinely cannot name what it was.