Ok well thats good about the skull. It may be a birthmark, although this is not common. If you can keep him away from mom now would probably be better so she doesn't keep opening it up. Not knowing what the cause is of the growth,(for lack of a better word) is would make it hard to decide if it can be removed surgically. You will probably have to let him grow a little more before making that kind of decision. It could be a blood vessel that has grown incorrectly and creates this bubble. It might be able to be tied off when he is a little older if that is the case and if it is not attached to something critical.
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