Mom! I have a cheap area rug that I use in my pottery booth. According to its tag, it's made of "100% Undetermined Fiber". Does that mean nobody at the carpet mill has the foggiest idea what the thing's made of? Does a dump truck just back up to the loading dock and dump off a bunch of leftovers from the mills that make real carpet?

"Here ya go, guys. Big ol' pile of some sort of thready lookin' shit. See if ya'll can make rugs out of it."

Is "100% Undetermined Fiber" the carpet maker's equivalent of mystery meat?