chalaza [kuh-ley-zuh] noun
Plural is chalazae [kuh-ley-zee]
Thick, white strands of protein found in bird and reptile eggs. Chalazae are attached to the two ends of the egg yolk, anchoring it in the center of the white. The more pronounced the strands are, the fresher the egg.
Some bakers will ask for a refinement when separating eggs and suggest removing the chalazae. We hardly ever bother in the test kitchen, with the exception being when we are making custards. You could strain the custard after cooking, which would strain the hardened strands out, but we find it easier to remove them first while the eggs are still raw. Crack your eggs into a bowl one at a time and use a fork to fish out each chalaza.