What Causes Dark Strings In Sputum With History Of Chronic Asthma?

I have been coughing up mucous for years some tainted black as i am a smoker with asthma but latley I have been noticing that there seems to be thick gummy stretchable worms in sputum that almost always seem to have a prong like top.all have a black looking lets say vein like you would remove from a shriimp when cleaning. I have chronic asthma have been exposed to TB but treated. HIV and HepC exposure cleared with no interfuron nondetectable