A chalaza is a twisted, rope-like structure found in the egg of birds, including chickens. It helps anchor the yolk in the center of the egg, providing stability during movement. This feature is important for the development of the embryo, as it keeps the yolk in place and ensures that the egg white surrounds it evenly. Chalazae are typically visible as two white strands on either side of the yolk when an egg is cracked open. They are made of protein and are a natural part of the egg's structure. The presence of chalazae indicates that the egg is fresh and has not been overly processed.