Writing on duck eggs

[LynMcLean]

My Duck is sitting on her eggs, and today I was able to candle four of them (there's a lot more but she and the drake were getting upset). One of the eggs had veins and movement. I want to mark which one(s) are developing but I know that pencil will wear off. What can I safely use to mark them?

 

[BirdsBeesTrees]

I use Crayola markers they are for kids and are nontoxic.

 

[sylviethecochin]

I've used permanent markers for several years with no noticeable ill effects.

 

[Pennys Mama]

I use a fine tip sharpie

 

[LynMcLean]

Thank you, I used a brown crayola marker to mark my 12 developing eggs.

 

[Miss Lydia]

I use a fine tip sharpie

This is what I use too.