Where did you find that- in an egg?
It's possible it could be part of the egg called the chalaza. Which is basically anchors the yolk in place.
It could also be a worm?
You can use Valbazen 1/2 ml orally and then repeated in 10 days for each chicken or Fenbendazole (Safeguard, Panacur) at 1/4 ml per pound for 5 days in a row.