There were guesses of horse hair, human hair, a tumbleweed as well as other things. Actually, to be honest, I had to ask and had to be told. I thought it was horse hair, too, cause it felt that scratchy.
However, the answer is .................
A hair ball from a cow. If you have seen a hair ball from a cat, it's not too large and is not round. However, if a cow gets a hairball (and it is COW hair, from licking itself and other cows), it stays in one of the three stomachs and churns round and round and round, making it round (of course).
It is only discovered after butchering when the stomach is opened (for what reason, I'll never know). Can you imagine?