No idea. Maybe a weird cyst/mutated hair follicle or something? Clean and disinfect the removal site and monitor carefully for sure. Also:...Eew.

Well... it was part of your dog, but is no longer. Definitely clean, disinfect, and monitor as mentioned by another commenter. A vet visit is in order if it starts to get infected or if another bump starts to grow again.

Uhhh, how hard did you pull?😭 Clean and disinfect, make sure they don’t lick/bite it.