“That looks like water wear to me. To asymmetrical for human wear.”
Unfortunately I agree. I want to root for it being an artifact but it is natural. If human made it would only have scoop wear like that in one place, that has scoop wear over the whole top were much of it would be impractical for real use of any kind.
It’s called an omarolluck. https://en.wikipedia.org/wiki/Omarolluk
Well, may it was a drunkard’s firestarter (the asymmetrical thing).