Weird blue on newly hatched chick

[blades]

So one of our chicks just hatched. It has a turquoise bluish marking on its bottom. Any ideas what it is from? Has anyone seen this before?

 

[Silkie-Feet]

I have never seen that before. If I had to guess than I would say it got stained after hatching (by walking on newspaper or something else with ink). If it occurred before hatch I would assume you used marker to mark X's and O's on each side and perhaps that ink managed to bleed through. Sorry I'm not much help, but that's my best guess.

 

[blades]

So I just realized what it's from. In the water tray I put a drop of blue food coloring in the water because I can never tell if it is full! Lol it must have touched it lol!!