Help! whats wrong with my ducklings

[Sae]

I have two ducklings and they both have this exact things on the backs of their necks. It appears to be white goo. It looks identical on both babies?!?

 

[Magnolia Ducks]

Does it wash off?
How old are they?
What are you feeding?
What kind of bedding are you using?

 

[Isaac 0]

Looks like some type of paint?

 

[Sae]

Thank you for the replies. I think i freaked out over nothing. I was like a slimy white substance... i have nooo idea where it came from. I almost wonder if mom had found.. something and and then touched them with her bill?? Possibly egg white from a random broken egg somewhere in the yard?? It disappeared after they swam and i havent seen it since! But she does nibble them in that area as if shes "checking on them". But i think i just panicked because it was the same on both babies thanks again everyone

 

[Sae]

Does it wash off?
How old are they?
What are you feeding?
What kind of bedding are you using?

It did wash off, they are almost two weeks, they eat baby crumbles and i use wood shavings, could any of that have done it?!

 

[Magnolia Ducks]

Just probably something they got into. Baby duck crumbles?