How to tell if it's real fleece?

A friend had the fleece on the under-side of his saddle replaced. He was asked/paid for real fleece, but it looks like fake/polyester fleece. How can he tell for sure? TIA.

Match? Clip off a few tiny tufts and try to burn it

pull out a few threads and light it
real wool will smell more like burning flesh while poly will smell plastic

real wool will form a sort of bubble that will crumble when you rub between your fingers while poly will form a hard bubble

real wool smells different from poly when it gets wet/sweaty

Thanks Y’all !!