Is the bump on my head the Occipital protuberance or a cyst??????

Hi I know this question has frequently been asked here, but I just gotta know. I have a bump on the back of my head, where the skull connects to the neck. No pain, very hard and perfectly centered. I only noticed it around 2 months ago, and can’t really tell if it has been there before or it grew in any way. I have no unusual symptoms. It’s got 1cm diameter and stands out around 0.5cm. I have a generally poor posture. Is this something to worry about like a cyst or can I ignore it?