I don't know, it looks like it might be a tapeworm. Several types can infect poultry when they eat earthworms and insects. Not all are segmented either, but the picture does show a few sections on the upper right side that look like segmentation. I don't remember ever reading about a tapeworm moving into an egg, but I don't see why it would not be theoretically possible. The larval stage of the worm moves through the various tissues of the body, including leading to cysts that can form in muscle tissue. I think it would be possible for part of worm or larvae to move into the ovum and begin to develop inside an egg. I don't know, but it seems plausible. Or, it might just be a plain ole rubber band. LOL