Bumps on vent

[Foodforestchickens]

Hey everyone! I am in need of assistance/confirmation on what these little white head bumps are on one of my dark Cornish vents. Thank you very much in advance

 

[PennelopeSpeaks]

Could it be crusted on poop?

 

[Foodforestchickens]

There is most definitely some crusted on poop as well. Looking at the photo at the top corner of the vent you can really see a couple white head like structures. Thank you!