I just found that one of my chicks died earlier and I checked it out to see what was going on until I threw it out (it was 4 days old). It looked like there was a wound below vent, which must have been the belly button. the belly button had a hard coat of something yellow (my guess is the yolk). I picked at it and an amount of the yellow liquid came oozing out. Is this the yolk and is it supposed to be there? Anyone know why it died?