Just had one come out like that and she's doing great. Its an umbilical hernia, its probably yolk. Your biggest danger is infection. Put some kind of drying agent/antiseptic on it. I use Wonder Dust and I highly recommend it, if you don't have any, they probably sell it at your local feed store and I would put iodine, betadine or (last choice) triple antibiotic ointment on it. But you really want to dry it up.