Would you find the cotton on Q-tips as it was when it went in, or would it disintegrate after a very long time?

You mean if some cotton got stuck in the wax inside an ear? It would come out with the wax and/or water from showering etc eventually, unless the wax flow got blocked, in which case it’d be there until it got cleared out, but it would start to decompose.

According to this article , perhaps six months, but I think it might take a bit longer especially sealed in earwax which might tend to preserve it. That article is talking about an outdoor compost heap, which is a different environment. Certainly cotton can last for decades in a drawer somewhere. I imagine an ear canal tends to be more like a drawer than a compost heap, and that it’d tend to get cleared out before it decomposed.

Thanks @Zaku.