Hello I am new to the forum I thought that this would be my best chance to find out what this might be. I found this 1.5ml microcentrifuge tube under the couch cushions in my home. I asked the other members of my family if it was there's or if they knew what it was and nobody had an answer. These photos are the best I could take and the only other information I could share is it looks like a used cigarette filter breaking down or some type of cotton fiber maybe and I also carefully opened it to see if there was an odor and it smelt like isopropyl alcohol. I originally thought maybe a illicit substance at first because I do have teenage children and there friends do visit but I don't suspect it is even though you can never be certain my kids are extremely open and honest with my wife and I. If anyone can help I would greatly appreciate it and thank you in advance.

Could it be a laboratory specimen sample of some sort and IPA is being used as preservative/carrier?

Yeah, I wondered if a family member worked in a healthcare facility, had put a sample in a pocket and then forgotten it was there.  Couches tend to acquire items that fall out of pockets.  The fact that you know it's a 1.5 ml microcentrifuge tube would suggest you have some acquaintance with that line of work.