Marking Eggs

[GoldenPooper]

HI, this may be a stupid question. But what does everyone use to mark their hatching eggs? I am not sure if you can use a sharpie, because they are not non-toxic? Just want to see what everyone uses when marking their eggs.
Thanks

 

[Pyxis]

I just use a pencil

 

[GoldenPooper]

That is what I was planning to use, but was worried about it rubbing off.