What all could it be? Dr. Google tells me a swollen lymph node is the most common cause. Its hard, immoveable, painless and pea sized. On the same side as my CH (which I am sure is a coincidence but it makes you wonder...) Mentioned it last year to my GP who said she couldn't feel it. Just realized I never mentioned it to my neurotologist because my GP told me to forget about it and well... I did forget about it... until recently when I found it again. CT scan last year was clear.
You might be right, I thought that's what the hard bone right behind the ear lobe was called though. I very well could be wrong. I often am. LOL