Pencil rubbing off eggs

[Pollux]

My pencil markings are rubbing off the eggs my broody hen is sitting on. Is there any other way I can mark them? Thank you.

 

[LilPeeps]

I use a sharpie.

 

[Pollux]

and the ink doesnt harm the eggs? - i thought they were porous.

 

[aberfitch]

sharpies dries in seconds and is non toxic.

 

[Pollux]

thank you both.