I suspect it is originating from the mud. This has some plastic bits with it. They are spreading all over my walls. I think it is some kind of cocoon for worm. Should it's rapid growth in terms of number be a matter of concern? found in Bangalore, India,
Bagworms? https://en.wikipedia.org/wiki/Bagworm_moth I don't know how destructive individual species are. They probably aren't more than an aesthetic concern.