Looks like yolk on the incubator tray. I'd probably drip some iodine on it and leave it since the chick is sitting up and looks OK. Try and keep it clean and make sure the other ones don't pick at its navel. You could leave it in the incubator and keep the humidity high to see if it absorbs any but I doubt it will.
Copy, thank you. I did that last night just in case. It dried up and fell off. I also cleaned the incubator and put them back in there for a little more. Thank you for the quick response.