I've had these (or at least something very similar) and have seen many other people describe something like it. One time I opened one up with scissors. It had hollow chambers inside and was very tough in texture. I think it has to be some sort of egg sac because of the way mine came out together and when I was feeling very sick from a cleanse. During a successful cleanse these "cotton balls" were followed by a large worm. Actually one time I think I passed the worm first. If it was any type of food particle the texture would be very soft and nothing like what I've seen.