What is this and is it threatening my ducklings life?

[Ducklets1999]

Does anyone happen to know what this pink/ black thing on my duckling, I had to assist with hatching as the duckling was stuck behind the membrane for nearly 2/3 days, just want to know if the duckling will sort it itself, or if it needs something more, never come across this? I have been keeping it clean

 

[SilverBirds]

That his belly button .It looks like it still has a bit of the umbilical cord on it. It should just dry up and fall off within a few days!