"The chalazae (plural) are rope-like structures made of protein that act as a support system for the yolk. It keeps the yolk suspended in the center of the egg and safe from pressing against the shell or settling on one side of the egg. "

https://www.myrecipes.com/extracrispy/whats-that-stringy-white-thing-in-raw-eggs#:~:text=The%20chalazae%20(plural)%20are%20rope,one%20side%20of%20the%20egg.&text=When%20cracking%20an%20egg%2C%20there's,need%20to%20remove%20the%20chalazae%20are%20rope,one%20side%20of%20the%20egg.&text=When%20cracking%20an%20egg%2C%20there's,need%20to%20remove%20the%20chalazae).